Agilent Technologies 3458A Multimeter User’s Guide Manual Part Number: 03458-90014 Printed in U.S.
AGILENT TECHNOLOGIES WARRANTY STATEMENT AGILENT PRODUCT: 3458A Multimeter DURATION OF WARRANTY: 1 year 1. Agilent Technologies warrants Agilent hardware, accessories and supplies against defects in materials and workmanship for the period specified above. If Agilent receives notice of such defects during the warranty period, Agilent will, at its option, either repair or replace products which prove to be defective. Replacement products may be either new or like-new. 2.
Documentation History All Editions and Updates of this manual and their creation date are listed below. The first Edition of the manual is Edition 1. The Edition number increments by 1 whenever the manual is revised. Updates, which are issued between Editions, contain replacement pages to correct or add additional information to the current Edition of the manual. Whenever a new Edition is created, it will contain all of the Update information for the previous Edition.
DECLARATION OF CONFORMITY According to ISO/IEC Guide 22 and CEN/CENELEC EN 45014 Manufacturer’s Name: Manufacturer’s Address: Agilent Technologies, Incorporated 815 14th ST. S.W. Loveland, CO 80537 USA Declares, that the product Product Name: Model Number: Product Options: Multimeter 3458A This declaration covers all options of the above product(s).
Preface This manual contains installation information, operating and programming information, and configuration information for the 3458A Multimeter. The manual consists of the following chapters: Chapter 1 Installation and Maintenance This chapter contains information on initial inspection, installation, and maintenance. It also contains lists of the multimeter' s available options and accessories. Chapter 2 Getting Started This chapter covers the fundamentals of multimeter operation.
Contents Chapter 1 Installation and Maintenance Introduction ........................................................... 15 Initial Inspection .................................................... 15 Options and Accessories ........................................ 16 Installing the Multimeter ....................................... 17 Grounding Requirements ................................. 17 Line Power Requirements ................................ 17 Setting the Line Voltage Switches ...................
Deleting States .................................................. 75 Using the Input Buffer ........................................... 75 Using the Status Register ....................................... 75 Reading the Status Register .............................. 77 Interrupts .......................................................... 77 Chapter 4 Making Measurements Introduction ........................................................... 81 Triggering Measurements ......................................
APER .............................................................. 160 ARANGE ....................................................... 160 AUXERR? ...................................................... 161 AZERO ........................................................... 162 BEEP .............................................................. 164 CAL ................................................................ 164 CALL .............................................................. 164 CALNUM? ...........
Math Operations ............................................. 262 Subprogram Definition/Deletion .................... 263 Subprogram Execution Commands ................ 263 Looping and Branching .................................. 263 Binary Programs ............................................. 263 New Multimeter Commands ............................... 264 3458A BASIC Language Example Program ....... 265 Variables and Arrays ........................................... 266 Type Declarations ................
Capturing the Data ............................................... 352 High Speed Data Transfers .................................. 355 Software Help The Wave Form Analysis Library 355 Starter Main Program ..................................... 357 Errors in Measurements ...................................... 358 Amplitude Errors ........................................... 359 Trigger and Timebase Errors .........................
Contents
Chapter 1 Installation and Maintenance Introduction ........................................................... 15 Initial Inspection .................................................... 15 Options and Accessories ........................................ 16 Installing the Multimeter ....................................... 17 Grounding Requirements ................................. 17 Line Power Requirements ................................ 17 Setting the Line Voltage Switches ...................
Chapter 1 Installation and Maintenance
Chapter 1 Installation and Maintenance Introduction This chapter contains information on initial inspection, installation, and maintenance. It also contains lists of the multimeter's available options and accessories. It's a good idea to read this chapter before making any electrical connections to the multimeter. Initial Inspection WARNING If any of the following symptoms exist, or are expected, remove the multimeter from service: 1. 2. 3. 4. Visible damage. Severe transport stress.
Options and Accessories Table 1 lists the available options, and Table 2 lists the available accessories for the multimeter. Table 1.
Installing the Multimeter This section discusses the multimeter's grounding and power requirements and contains instructions for installing the multimeter. (Refer to Appendix C for instructions on how to install the switch lockout caps.) Figure 1 shows the multimeter's rear panel. Many of the rear panel connectors and switches are referenced in this section. Figure 1. Rear panel Grounding Requirements WARNING The multimeter comes with a three-conductor AC power cable (see Figure 3).
Table 3. Line Voltage Limits Nominal Value (RMS) 100 VAC 120 VAC 220 VAC 240 VAC Setting the Line Voltage Switches Allowable Limits (RMS) 90 VAC to 110 VAC 108 VAC to 132 VAC 198 VAC to 242 VAC 216 VAC to 250 VAC The line voltage selection is pre configured according to the country to which it is shipped. Use the following procedure if you need to change this setting: 1. Remove the multimeter's line power cord before changing the positions of the AC line voltage selection switches 2.
Power Cords Australia Denmark Europe Great Brittain Switzerland U.S.A Country Part Number Option Voltage Australia 8120-1369 901 250V 6A Denmark 1820-2956 912 259V 6A Europe 1820-1689 902 250V 6A Great Brittain 1820-1351 900 250V 6A Switzerland 1820-2104 906 250V 6A United States 1820-1378 903 120 10A United States 1820-0698 904 240V 10A U.S.A. Power cords supplied by Agilent have polarities matched to the power input socket on the instrument.
Figure 4. Typical GPIB Connections A total of 15 devices can be connected together on the same GPIB bus. The cables have single male/female connectors on each end so that several cables can be stacked. The length of the GPIB cables must not exceed 20 meters (65 feet) total, or 2 meters (6.5 feet) per device, whichever is less. 20 The GPIB Address You can change the multimeter's GPIB address using the ADDRESS command.
Installation Verification The following program verifies that the multimeter is operating and can communicate with the controller over the GPIB bus. 10 20 30 40 50 PRINTER IS 1 OUTPUT 722;"ID?" ENTER 722; IDENT$ PRINT IDENT$ END If the multimeter has been correctly installed, the message HP 3458A will be printed on the designated system printer. If no message is printed, make sure power is applied to the multimeter.
Figure 5. Current Terminal/Fuse Assembly 22 Repair Service You may have the multimeter repaired at an Agilent Technologies service center whether it is under warranty or not. Contact the nearest Agilent Sales Office for shipping instructions prior to returning the instrument. Serial Number Agilent instruments are identified by a two part, ten-character serial number of the form 0000A00000. The first four digits are the same for all identical products.
Chapter 2 Getting Started Introduction ........................................................... 25 Before Applying Power ......................................... 25 Applying Power ..................................................... 25 Power-On Self-Test .......................................... 25 Power-On State ................................................. 25 The Display ...................................................... 26 Operating from the Front Panel .............................
Chapter 2 Getting Started
Chapter 2 Getting Started Introduction This chapter is intended for the novice multimeter user. It shows you how to use the multimeter's front panel, how to send commands to the multimeter from remote, and how to retrieve data from remote. Since front panel operation is discussed first, it covers important topics such as the power-on state, display annunciators, the various ways to select or enter parameters, and how to make a simple DC voltage measurement.
Table 5.
Table 6.
Making a Measurement In the power-on state, DC voltage measurements are selected and the multimeter automatically triggers and selects the range. In the power-on state, you can make DC voltage measurements simply by connecting a DC voltage to the input terminals as shown in Figure 7. The connections shown in Figure 7 also apply for AC voltage, 2-wire resistance, AC+DC voltage, digitizing, and frequency or period measurements from a voltage input source.
Table 7. Function Keys In addition to the functions selected by the FUNCTION keys, the multimeter can perform direct-sampled or sub-sampled digitizing, ratio measurements, and AC or AC+DC voltage measurements using the synchronous or random measurement methods. These functions can be selected from the front panel by accessing the appropriate command(s) using the alphabetic menu keys (these keys are discussed later in this section under "Using the MENU Keys").
Notice the display's MRNG (manual range) annunciator is on. This annunciator is on whenever you are not using autorange. Manual Ranging The second choice lets you manually select the range. When the multimeter is in the measurement mode (that is, the multimeter is making and displaying measurements or the display is showing OVLD) you can change the range by pressing the up or down arrow keys.
If the self-test failed, one or more error conditions have been detected. Refer to the next section "Reading the Error Register". Reading the Error Register Whenever the display's ERR annunciator is illuminated, one or more errors have been detected. A record of hardware errors is stored in the auxiliary error register. A record of programming and syntax errors is stored in the error register.
(unshifted). Resetting the Multimeter Many times during operation, you may wish to return to the power-on state. The front panel Reset key returns you to the power-on state without having to cycle the multimeter's power. To reset the multimeter, press: Reset The multimeter begins the reset process with a display test which illuminates all display elements including the annunciators as shown in Figure 8. (By holding down the Reset key, the multimeter continuously performs its display test). Figure 8.
Table 8. Configuration Key Functions We will use the Trig key to demonstrate how to use the configuration keys. Press: Trig The display shows: This is the command header for the trigger command. Notice the multimeter automatically placed a space after the command header. Selecting a Parameter For parameters that have a list of choices (non-numeric parameters), you can use the up and down arrow keys to review the choices.
Press: The display shows: When using the up or down arrow keys, if you step past the last parameter choice, a wraparound occurs to the other end of the menu. Suppose you want to suspend triggering. Press the up or down arrow key until the display shows: Press: Enter You have now changed the trigger event from auto (power-on state) to HOLD which causes the multimeter to stop taking readings. (Triggering is discussed in detail in Chapter 4.) Default Values Most parameters have a default value.
demonstrate numeric parameters. Press: NPLC This display shows: Notice that if you press the up or down arrow key, no parameter choice is displayed. This means there is no menu and you must enter a number. For example, press: Enter 1 You have now selected 1 power line cycle of integration time for the A/D converter. Integration time is the actual time that the A/D converter measures the input signal. (Integration time is discussed in detail in Chapter 3.
The second parameter of the NRDGS command specifies the event that initiates each reading. Since this is not a numeric parameter, a menu is available for this parameter. Use the up or down arrow keys to cycle through the list of choices. When the display shows: Execute the command by pressing: Enter You have now selected five readings per trigger event. If you execute the TRIG SGL command, for example, the multimeter will take five readings and then stop.
eliminates the GPIB bus-related commands, commands that are seldom used from the front panel, and any commands that have dedicated front panel keys (e.g., the NPLC key or the Trig key). Query Commands Standard Queries There are a number of commands in the alphabetic command directory that end with a question mark. These commands are called query commands since each returns a response to a particular question. For example, access the LINE? query command from the command menu and press the Enter key.
Clear Back Space Display Editing The Back Space key allows you to edit parts of a command string while entering the string or when the string is recalled (discussed later), For alpha parameters or command headers, pressing the Back Space key once erases the entire parameter or header. For commas, spaces, and numeric parameters, only one character is erased each time you press Back Space.
arrow keys. MORE INFO Display In addition to scrolling the display left and right, the Display/Window keys allow you to view additional display information when the display's MORE INFO annunciator is illuminated. For example, access and execute the SETACV RNDM command from the alphabetic command menu. Now press the front panel ACV key. Notice that the multimeter's MORE INFO annunciator is illuminated. This means there is more information available than is being displayed.
User-Defined Keys You can assign a string of one or more commands to each of the USER keys labeled f0 - f9. After assigning a string to one of these keys (maximum string length is 40 characters), pressing that key displays the string on the display. You can then execute the string by pressing the Enter key. The Def Key allows you to assign a command string to any of the user-defined keys.
this section. After editing the string, press the Enter key to execute the string. (The previous string is still assigned to the user-defined key.) An edited string cannot be re-assigned to a user-defined key. If you want to change a key definition, you must repeat the above steps. Installing the Keyboard Overlay Figure 9 shows the keyboard over-lay that fits over the USER keys. You can write on this overlay with a pencil to identify the command(s) assigned to each user-defined key. Figure 9.
Figure 10. Installing the keyboard overlay Operating from Remote This section shows you the fundamentals of operating the multimeter from remote. This includes reading and changing the GPIB address, sending a command to the multimeter, and retrieving data from the multimeter. Input/Output Statements The statements used to operate the multimeter from remote depend on the computer and its language. In particular, you need to know the statements the computer uses to input and output information.
A typical display is: The displayed response is the device address. When sending a remote command, you append this address to the GPIB interface's select code (normally 7). For example, if the select code is 7 and the device address is 22, the combination is 722. Changing the GPIB Address Every device on the GPIB bus must have a unique address.
30 END The same technique allows you to get readings from the multimeter. Whenever the multimeter is making measurements and you have not enabled reading memory (reading memory is discussed in Chapter 4), you can get a reading by running the following program. 10 ENTER 722;A 20 PRINT A 30 END The Local Key When you press a key on the multimeter's keyboard while operating from remote, the multimeter does not respond.
Chapter 3 Configuring for Measurements Introduction ........................................................... 47 General Configuration ........................................... 47 Self-Test ........................................................... 47 Reading the Error Registers ............................. 48 Calibration ........................................................ 48 Autocalibration ............................................ 48 Running Autocal ........................................
Chapter 3 Configuring for Measurements
Chapter 3 Configuring for Measurements Introduction This chapter shows how to configure the multimeter for all types of measurements except digitizing.1 This chapter also shows you how to use subprogram and state memory, the input buffer, and the status register. After using this chapter to configure the multimeter for your application, you can then use Chapter 4 to learn how to trigger readings and transfer them to reading memory or the GBIB output buffer.
annunciator illuminates. Reading the Error Registers When a hardware error is detected, the multimeter sets a bit in the auxiliary, error register and also sets bit 0 in the error register.When a programming error is detected, the multimeter sets a bit in the error register only. The ERRSTR? command reads each error (one error at a time) and then clears the corresponding bit.
routine are: • The DCV routine enhances all measurement functions. This routine takes about 1 minute to perform. • The AC routine performs specific enhancements for AC or AC+DC voltage (all measurement methods), AC or AC+DC current, direct- or sub-sampled digitizing (AC- or DC-coupled), frequency, and period measurements. The AC routine takes about 1 minute to perform. • The OHMS routine performs specific enhancements for 2 or 4-wire ohms. DC current, and AC current measurements.
the CALSTR command; this can be read later using the CALSTR? command.) The following example shows how to use the TEMP? command to monitor the multimeter's internal temperature (in degrees Celsius). 10 20 30 40 OUTPUT 722;"TEMP?" ENTER 722;A PRINT A END The autocal constants are stored in continuous memory (they remain intact when power is removed). Therefore, it is not necessary to perform autocal simply because power has been cycled.
Table 9: Input Ratings Rated Input Maximum NonDestructive Input HI/LO W Sense to LO Input: ± 200V peak ± 350V peak HI to LO W Sense:Input: ± 200V peak ± 350V peak LO Input to Guard: ± 200V peak ± 350V peak Guard to Earth Ground: ± 500V peak ± 1000V peak HI/LO Input, HI/LO W Sense, or I terminal to earth ground: ± l000V peak ± 1500V peak Front terminals to rear terminals: ± l000V peak ± l500V peak The multimeter will be damaged if any of the above maximum non-destructive inputs are exceed
Presetting the Multimeter The PRESET NORM command is similar to the RESET command but configures the multimeter to a good starting point for remote operation. (RESET is primarily for front panel use.) It's a good idea to execute PRESET NORM as the first step when configuring the multimeter since it sets the multimeter to a known configuration and suspends readings by setting the trigger event to synchronous (TRIG SYN) command. Table 10 shows the commands executed by the PRESET NORM command.
30 END In addition to the PRESET NORM command, the multimeter has a PRESET FAST command (configures for fast readings and transfers), which is discussed in Chapter 4, and a PRESET DIG command (configures for DCV digitizing) which is discussed in Chapter 5. Specifying a Measurement Function The first parameter of the FUNC command selects the measurement function. For example, to specify DC voltage measurements, send: OUTPUT 722;"FUNC DCV" The FUNC command header is optional and can be omitted.
OUTPUT 722;"ARANGE ONCE" Now when triggering begins, the multimeter will select the correct range and then disable autorange. Later, if you need to enable autorange, send: OUTPUT 722; "ARANGE ON" Specifying the Range You specify a fixed range using the first parameter of one of the function commands (ACV, DCV, OHM. etc.) or the RANGE command. This parameter is called max._inputsince you specify it as the input signal's maximum expected amplitude (or the maximum resistance for resistance measurements).
DC voltage measurements on the 1V range, send: OUTPUT 722;"DCV 1" Table 12: DC Voltage Ranges DCV Range Full Scale Reading Maximum Resolution Input Resistance 100mV 120.00000mV 10nV >10GW* 1V 1.20000000V 10nV >lOGW* 10V 12.0000000V 100nV >lOGW* 100V 120.000000V 1µV 10MW 1000V 1050.00000V 10µV 1OMW * With FIXEDZ OFF. With FIXEDZ ON the input resistance is fixed at 10MW. Refer to Fixed Input Resistance later in this chapter for more information. Figure 11.
OUTPUT 722;"DCI 10E-6" Table 13: DC Current Ranges DCI Range Full Scale Reading Maximum Resolution Shunt Resistor lOOnA 120.000nA 1pA 545.2kW 1µA 1.200000µA 1pA 45.2kW 10µA 12.000000µA 1pA 5.2kW 100µA 120.00000µA 10pA 730W 1mA 1.2000000mA lOOpA 100W 10mA 12.000000mA 1nA 10W 100mA 120.00000mA 10nA 1W 1A 1.0500000A 100nA 0.1W Figure 12.
Table 14: Resistance Ranges OHM(F) Range Full Scale Reading Maximum Resolution Current Sourced 10MW 12.000000MW 1W 500nA 100MW 120.00000MW 10W 500nA 1GW 1.2000000GW 100W 500nA 2-Wire Ohms Two-wire ohms is most commonly used when the resistance of the test leads is much less than the value being measured. If the lead resistance is large compared to the resistance to be measured, readings will be inaccurate. For example, suppose you are measuring a 1W resistor located 10 feet away.
Figure 14. 4-Wire ohms measurement connections Configuring the A/D Converter The A/D converter's configuration determines the measurement speed, resolution, accuracy, and normal mode rejection1 for DC or ohms measurements. The factors that affect the A/D converter's configuration are the reference frequency, the specified integration time, and the specified resolution.
the multimeter has a power line frequency of 60 Hz and the device being measured has a power line frequency of 50 Hz. For this application you can achieve NMR by setting the reference frequency to 50 Hz as follows: OUTPUT 722;"LFREQ 50" Remember that whenever power is cycled or the front panel Reset key is pressed, the reference frequency returns to the rounded value of 50 or 60 Hz. Setting the Integration Time Integration time is the period of time that the A/D converter measures the input signal.
select the integration time that provides adequate speed while maintaining an acceptable amount of resolution and NMR. The specifications tables in Appendix A show the relationship of integration time to digits of resolution and NMR for DC and ohms measurements. Specifying Integration Time Directly For DC or ohms measurements, you can specify the integration time directly (in seconds) using the APER (aperture) command. For example, to specify 22 ms of integration time, send: OUTPUT 722;"APER.
For DC or ohms measurements (and analog AC measurements), resolution is determined by the A/D converter's integration time. When you specify a resolution, you are actually indirectly specifying an integration time. Since the APER or NPLC command can also specify an integration time, an interaction occurs when you specify resolution as follows: • If you send the APER or NPLC command before specifying resolution, the multimeter satisfies the command that specifies greater resolution (more integration time).
inaccurate 4-wire ohms measurements. Offset Compensation Because a resistance measurement involves measuring the voltage induced across the resistance, any external voltage present (offset voltage) will affect the measurement accuracy. With offset compensation enabled, the multimeter corrects resistance measurements by canceling the effects of the offset voltage. To do this, the multimeter first measures the input voltage with its current source on.
frequency ranges shown in Table 15. Notice that when measuring AC+DC voltage using the analog method, for example, any AC components below 10Hz are not included in the measurement. Note When taking measurements on the 10mV and 100mV ranges using any AC measurement method, it is possible for radiated noise (such as transients caused large motors turning on and off) to cause inaccurate readings.
Analog RMS Conversion The analog RMS conversion directly integrates the input signal and is the method selected when power is applied. This method works well for measuring signals in the frequency range of 10 Hz to 2 MHz and can provide the fastest reading rate of the three methods. Random Sampling Conversion The random sampling conversion takes numerous samples of the input signal for each reading generated.
measures the DC component and the AC component with frequencies > 10Hz. Notice that when measuring AC+DC current, any AC components below 10Hz are not included in the measurement. The maximum resolution for AC or AC+DC current is 6½, digits. Table 16 shows each current range and its full scale reading, maximum resolution, and the shunt resistor used. (Resolution is a function of the specified integration time; refer to Setting the Integration Time, later in this section, for more information.
LEVEL command in Chapter 6 for more information. Table 17: FSOURCE Parameters FSOURCE Parameter Definition Measurement Capabilities Frequency Period ACV AC-coupled AC voltage input 1Hz — 10MHz 100ns — 1s ACDCV DC-coupled AC voltage input 1Hz — 10MHz 100ns — 1s ACI AC-coupled AC current input 1Hz — 100kHz 10ms — 1s ACDCI DC-coupled AC current input 1Hz — 100kHz 10ms — 1s The following program configures the multimeter for frequency measurements on the 10V range from a voltage Source.
important that the specified bandwidth (particularly the specified low frequency) corresponds to the frequency content of the input signal. Setting the Integration Time Integration time is the period of time that the A/D converter measures the input signal. For analog AC measurements, the integration time determines the maximum digits of resolution and, along with the specified bandwidth affects the measurement speed. (Integration time also has a minor affect on analog AC measurement accuracy).
if you specify 60 PLCs of integration time, the multimeter averages six 10 PLC readings. Typically, you should select the integration time that provides adequate speed while maintaining an acceptable amount of accuracy and resolution. Table 18 shows the relationships between integration time and digits of resolution for analog AC measurements. Table 18: Analog AC A/D Converter Relationships Digits of Resolution Specifying Resolution Power Line Cycles (NPLC command) LFREQ = 6OHz LFREQ = 5OHz 4.5 0 – .
For analog AC measurements, if you default, the %_ resolution parameter, the integration time will be that specified by the last NPLC command executed. For sampled ACV or ACDCV, random sampling (SETACV RNDM) has a fixed resolution of 4.5 digits that cannot be changed. For synchronous sampling (SETACV SYNC) a %_resolution parameter of 0.001 = 7.5 digits; 0.01 = 6.5 digits: 0. 1= 5.5 digits: and 1 = 4.5 digits.
percent for the synchronous conversion method or 0.4 percent for the random conversion method.) The following program selects AC voltage measurements using the synchronous sampling conversion. The maximum expected input voltage is 10 volts and a %_resolution parameter of .1 selects 5.5 digits resulting in an actual resolution of l mV. 10 OUTPUT 722; "SETACV SYNC" 20 OUTPUT 722;"ACV 10, .
Specifying Ratio Measurements To specify ratio measurements, you first select the measurement function for the signal measurement (and the measurement method for AC or AC+DC voltage) and then enable ratio measurements using the RATIO command. For example, the following program specifies AC voltage ratio measurements (on the 10V range) using the synchronous sampling conversion.
DCCUR1. 10 20 30 40 50 60 70 80 OUTPUT OUTPUT OUTPUT OUTPUT OUTPUT OUTPUT OUTPUT END 722;"SUB DCCUR1" 722;"MEM FIFO" 722;"TRIG HOLD" 722;"DCI 1,.01" 722; "NRDGS 5, AUTO" 722;"TRIG SGL" 722; "SUBEND" If you create a new subprogram using the same name as an existing subprogram, the new subprogram overwrites the old subprogram. Executing a Subprogram To execute a stored subprogram, issue the CALL command along with the subprogram's name.
Subprogram execution can also be resumed by sending the GPIB Group Execute Trigger (this does not in itself trigger a reading: it merely resumes subprogram operation). Nested Subprograms You can use a subprogram to call another subprogram (nested subprograms). For example, when the following subprogram is called (CALL 1 command), it takes 10 DC voltage readings and then calls the previously stored subprogram DCCUR1.
The following program statement compresses the previously stored subprogram named DCCUR1. OUTPUT 722; "COMPRESS DCCUR1" Deleting Subprograms The DELSUB command deletes a particular subprogram. For example, to delete the subprogram named DCCUR1 send: OUTPUT 722; "DELSUB DCCUR1" You can also delete all stored subprograms and all stored states using the SCRATCH command. Using State Memory You can store the multimeter's present configuration (measurement function. range, resolution, integration time, etc.
OUTPUT 722;"RSTATE ACST1" From the front panel, you can view all stored state names by accessing the RSTATE command and pressing the up or down arrow key. Once you have found the correct state, press Enter to recall the state. Deleting States You can delete a single stored state using the PURGE command. For example, to purge the state ACST1, send: OUTPUT 722;"PURGE ACST1" You can also use the SCRATCH command to delete all stored states and all subprograms from memory.
• Subprogram complete • High or low limit exceeded • SRQ command executed • Power turned-on • Ready for instructions • Error • Service requested • Data available. When one of these events occurs, it sets a corresponding bit, in the status register. The following list defines the meaning of each bit in the status register: Bit 0 (weight = 1) Subprogram Complete--a stored subprogram has been executed.
which removed the error bit but left bit 6 set, Bit 7 (weight = 128) Data Available--a reading or query response is available in the output buffer. Reading the Status Register The STB? query command reads the status register and returns the weighted sum of all set bits. The STB? command does not clear the status register. The following program uses the STB? command to read the contents of the status register. 10 20 30 40 OUTPUT 722.
enabled still respond to their corresponding conditions. They do not, however, set bit 6 or assert SRQ. The following program is an example of interrupts using HP Series 200/300 BASIC.
Chapter 4 Making Measurements Introduction ........................................................... 81 Triggering Measurements ...................................... 81 The Trigger Arm Event .................................... 82 The Trigger Event ............................................ 82 The Sample Event ............................................ 82 Event Choices ................................................... 82 Making Continuous Readings ..........................
Chapter 4 Making Measurements
Chapter 4 Making Measurements Introduction This chapter discusses the methods for triggering measurements, the reading formats, how to use reading memory, and how to transfer readings across the bus. This chapter also discusses how to increase the reading rate and GPIB bus transfer speed, how to measure the reading rate, how to use the multimeter's EXTOUT signal, and how to use the math operations.
The Trigger Arm Event When the specified trigger arm event occurs, it arms the multimeter's triggering mechanism. That is, the trigger arm event enables a subsequent trigger event. You specify the trigger arm event using the TARM command. The Trigger Event When the specified trigger event occurs (and the trigger arm event has already occurred), it enables a subsequent sample event. You specify the trigger event using the TRIG command.
OUTPUT 722;"TARM AUTO” !Resumes readings suspended by TARM HOLD, PRESET FAST, or PRESET DIG or OUTPUT 722; "TRIG AUTO" !Resumes readings suspended by TRIG HOLD or PRESET NORM Making Single Readings 10 20 30 40 50 60 70 80 90 The NRDGS command specifies the number of readings made per trigger event and the sample event that initiates each reading. In the power-on, RESET, PRESET NORM, or PRESET FAST state, the number of readings per trigger is set to 1 and the sample event is AUTO (NRDGS 1,AUTO).
50 60 70 80 90 OUTPUT 722;"NRDGS 10, AUTO" OUTPUT 722;"TRIG SGL" ENTER 722;Rdgs(*) PRINT Rdgs(*) END Multiple Trigger Arming !10 READINGS/TRIGGER, AUTO SAMPLE EVENT !TRIGGER READINGS !ENTER READINGS !DISPLAY READINGS The second parameter of the TARM command allows you to specify multiple trigger arming. When multiple trigger arming is specified, a single occurrence of the trigger arm event arms the multimeter the specified number of times. (The trigger arm event must be SGL for multiple arming.
"High-Speed Mode" later in this chapter for more information. In the following program, the PRESET NORM command sets the trigger event to synchronous. Line 40 specifies 15 readings per synchronous trigger event. Line 50 requests data from the multimeter. This satisfies the synchronous trigger event and initiates the readings. Notice that line 50 requests data from the multimeter 15 times.
with a 1 second interval between readings (this is shown in Figure 18). 10 20 30 40 50 60 70 OPTION BASE 1 DIM Rdgs(8) OUTPUT 722;"PRESET NORM" OUTPUT 722;"SWEEP 1,8" ENTER 722; Rdgs(*) PRINT Rdgs(*) END Note !COMPUTER ARRAY NUMBERING STARTS AT 1 !DIMENSION ARRAY FOR 8 READINGS !TARM AUTO, TRIG SYN, DCV AUTORANGE !1 SECOND INTERVAL, 8 READINGS/TRIGGER !SYN EVENT,ENTER EACH READING !PRINT READINGS 80 END When using the TIMER sample event or the SWEEP command, autorange is disabled.
Figure 19. DELAY with SWEEP (or TIMER) Default Delays If you have not specified a delay interval, the multimeter automatically determines a delay time (default delay time) based on the present measurement function, range, resolution, and the AC bandwidth setting. This delay time is actually the settling time allowed before readings, which ensures accurate measurements. The default delay time is updated automatically whenever the function range, resolution, or AC bandwidth changes.
The following example uses EXT as the sample event. The trigger event is synchronous (selected by the PRESET NORM command). The number of readings per trigger event is set to 10. When the controller executes line 50, the synchronous event occurs which enables the sample event (EXT). Upon the arrival of a negative edge transition on the Ext Trig terminal, the multimeter takes a single reading, which is transferred, to the controller.
Table 21. Event Combinations Trigger Arm Trigger Event Event Sample Event Description AUTO AUTO Any One reading is taken per sample event (if the sample event is AUTO, readings are taken continuously). AUTO EXT AUTO, EXT, TIMER, After a negative edge transition on the Ext Trig input, one LINE, LEVEL reading is taken per sample event until the specified number of readings are completed.
Table 21. Event Combinations Trigger Arm Trigger Event Event Sample Event Description EXT LINE AUTO, EXT, TIMER, After a negative edge transition on the Ext Trig input followed LINE by the power line voltage crossing zero volts, one reading is taken per sample event until the specified number of readings are completed.
Table 21. Event Combinations Trigger Arm Trigger Event Event Sample Event Description SGL SYN SYN After executing the TARM SGL command, followed by the controller requesting data2, which satisfies both SYN events, the first reading is taken. One reading is then taken per SYN event until the specified number of readings are completed.3 The trigger arm event then becomes HOLD.
Reading Formats This section discusses the ASCII, single integer (SINT), double integer (DINT). single real (SREAL), and double real (DREAL) formats that can be used for storing readings or for outputting readings on the GPIB. Storing readings in memory is described later in this chapter under "Using Reading Memory"; outputting readings on the GPIB is discussed later in this chapter under "Sending Readings Across the Bus".
Single Real The single real (SREAL) format conforms to IEEE-754 specifications. This format has 32 bits, 4 bytes per reading as follows: S EEE EEEE byte 0 E MMM MMMM byte 1 MMMM MMMM byte 2 MMMM MMMM byte 3 Where: S = sign bit (1 = negative 0 = positive) E = base two exponent biased by 127 (to "decode" these 8 bits, subtract 127 from their decimal equivalent). M = mantissa bits (those right of the radix point). There is an implied most significant bit (MSB) to the left of the radix point.
The SREAL number is then calculated by: -1 ´ 2-8 ´ 1.56471443177 = -6.
clearing any stored readings by sending: OUTPUT 722;"MEM CONT" Memory Formats Readings can be stored in one of five formats: ASCII, single integer (SINT), double integer (DINT), single real (SREAL), or double real (DREAL).
• ASCII This memory format can be used for any measurement function/multimeter configuration. Since ASCII has the greatest. number of bytes per reading, you should use it only when the output format is ASCII, measurement speed is not critical, and the number of readings to be stored is not great. The MFORMAT command specifies the reading memory format (the power-on and default format is SREAL).
in memory. 10 20 30 40 50 60 70 OUTPUT OUTPUT OUTPUT OUTPUT OUTPUT OUTPUT END 722;"TARM HOLD" 722."DCV 1" 722;"MEM FIFO" 722;"TRIG AUTO" 722;"NRDGS 10,AUTO" 722;"TARM SGL,8" !SUSPEND READINGS !DC VOLTAGE, 1V RANGE !ENABLE READING MEMORY, FIFO MODE !AUTO TRIGGER EVENT !10 READINGS/TRIGGER, AUTO SAMPLE EVENT !ARM TRIGGERING 8 TIMES The stored readings can now be accessed by individual reading number (1 "through 80) or by record/reading number (e.g. the 3rd reading in record 2 is also reading number 13).
10 OPTION BASE 1 20 DIM Rdgs(200) 30 OUTPUT 722;"PRESET NORM" 40 OUTPUT 722;"NRDGS 200,AUTO" 50 OUTPUT 722;"MEM FIFO" 60 OUTPUT 722;"TRIG SGL" 70 PAUSE 80 ENTER 722;Rdgs(*) 90 PRINT Rdgs(*) 100 END !COMPUTER ARRAY NUMBERING STARTS AT 1 !DIMENSION ARRAY FOR 200 READINGS !TARM AUTO, TRIG SYN, DCV AUTORANGE !200 READINGS/TRIGGER, AUTO SAMPLE EVENT !ENABLE READING MEMORY, FIFO MODE !TRIGGER READINGS !PAUSE PROGRAM, PRESS CONTINUE TO RESUME !ENTER READINGS !PRINT READINGS Sending Readings Across the Bus This s
Note When using the SINT or DINT memory/output format, the multimeter applies a scale factor to the readings. The scale factor is based on the multimeter’s measurement function, range, A/D converter setup, and enabled math operations. You should not use the SINT or DINT format for frequency or period measurements; when a real-time or post-process math operation is enabled (except STAT or PFAIL); or when autorange is enabled.
command is specific to Hewlett-Packard 200/300 controllers using BASlC language). The TRANSFER statement is the fastest way to transfer readings across the GPIB, especially when used with the direct memory access (DMA) GPIB interface. You should use the TRANSFER statement whenever measurement/transfer speed is important.
Using the SREAL Output Format The following program shows how to convert 10 readings output in the SREAL format.
readings to the computer using the DREAL format. The ENTER statement is easier to use since no I/O path is necessary but is much slower than the TRANSFER statement. Also when using the ENTER statement, you must use the FORMAT OFF command to instruct the controller to use its internal data structure instead of ASCII.
the output buffer when a new reading is available.) If reading memory is enabled in the FIFO mode and reading memory becomes full in the high-speed mode, the trigger arm event becomes HOLD which stops readings and removes the multimeter from the high-speed mode. After removing some or all of the readings from memory, you can resume measurements by changing the trigger arm event (TARM command).
Table 22: Commands Executed by PRESET FAST Command Reason DCV 10 Selects DC voltage measurements on the 10V range, which disables autorange. The autorange function samples the input before each reading, taking more time per reading than readings made on a fixed range. The disadvantage of a fixed range is lower resolution for signals that are less than 10% of full scale and the possibility of an overload condition for readings greater than full scale.
Frequency or period measurements: The integration time does not affect frequency or period measurements. For these measurements, the specified resolution (which also selects gate time) has a major effect on the reading rate. The specifications in Appendix A show reading rates for frequency and period measurements based on the specified resolution.
70 OUTPUT 722;"TARM SGL" 80 END High-Speed DCI Example 10 20 25 30 40 50 60 70 80 722;"MFORMAT SINT" 722;"MEM FIFO" 722;"DCI 100E-3" 722;"NRDGS 5000 AUTO" 722;"TARM SGL" Fast Synchronous ACV/ACDCV Example 10 20 30 40 50 60 70 80 90 OUTPUT OUTPUT OUTPUT OUTPUT OUTPUT OUTPUT OUTPUT OUTPUT END OUTPUT OUTPUT OUTPUT OUTPUT OUTPUT OUTPUT OUTPUT OUTPUT END 10 20 30 40 106 OUTPUT OUTPUT OUTPUT OUTPUT !TARM SYN, TRIG AUTO !SINT MEMORY FORMAT !ENABLE READING MEMORY !SYNCHRONOUS AC MEASUREMENT METHOD !AC VOL
50 OUTPUT 60 OUTPUT 70 OUTPUT 80 OUTPUT 90 OUTPUT 100 END 722;"ACV 10" 722;"NPLC 0.1"" 722;"ACBAND 10E3,20E3" 722;"NRDGS 100, AUTO" 722;"TARM SGL" Fast ACI/ ACDCI Example 10 20 30 40 50 60 70 80 90 OUTPUT OUTPUT OUTPUT OUTPUT OUTPUT OUTPUT OUTPUT OUTPUT END 10 20 30 40 50 60 70 80 OUTPUT OUTPUT OUTPUT OUTPUT OUTPUT OUTPUT OUTPUT END The following program measures AC current at a fast rate. This program uses the default delay time.
The following program transfers readings directly to the controller at the fastest possible rate. This program configures the multimeter to take readings at its maximum rate of >100k readings per second. Readings are output using the SINT format. If the bus/controller cannot transfer readings at >200k bytes per second, the reading rate will be slower.
The following program is an example of transferring readings from reading memory to the controller at the fastest possible rate. The program stores 5000 readings in reading memory using the SINT format. The readings are removed from memory using the "implied read" and transferred to the controller (in the SINT format) using the TRANSFER statement (line 130). The controller then retrieves the scale factor, multiplies the scale factor times each reading, and stores the corrected readings in the Rdgs array.
computer's timer.
the signal's polarity: NEG = low-going, POS = high-going. The events that can generate a signal on the Ext Out connector are: • Reading complete • Burst of readings complete • Input complete • Aperture waveform • Service Request • Executing the EXTOUT ONCE command Most of the above events apply to the multimeter's A/D converter. Figure 20 shows the relationship of these events to the A/D converter activity. Note The apparent time intervals shown in Figure 20 are for the illustration purposes only.
Figure 20. A/D Converter event relationships Reading Complete When specified, the reading complete event (RCOMP event) produces a 1 µs pulse following each reading for any measurement function. For sampled AC voltage measurements (SETACV SYNC or RNDM) a pulse is output after each computed reading, not after each sample in the measurement process. This event can be used to synchronize an external scanner to the multimeter when making one reading per scanner channel.
10 20 30 40 45 50 60 70 75 80 OUTPUT OUTPUT OUTPUT OUTPUT 722;"PRESET NORM" 722;"MEM FIFO" 722;"TRIG EXT" 722;"EXTOUT RCOMP,NEG" OUTPUT 709;"SADV EXTIN" OUTPUT 709;"CHCLOSED EXT" OUTPUT 709;"SCAN 201- 206" !DCV,NRDGS,l,AUTO, TARM AUTO, TRIG SYN !ENABLE READING MEMORY, FIFO MODE !TRIGGER EVENT = EXTERNAL !READING COMPLETE EXTOUT, LOW-GOING TTL !CONFIGURE EXTERNAL SCANNER !ADVANCE SCANNER ON MULTIMETER'S EXTOUT SIGNAL !OUTPUT LOW-GOING PULSE AFTER EACH CLOSURE !SCAN CHANNELS 01- 06 ON SCANNER IN SLOT 200
Input Complete 10 20 30 40 50 55 60 70 80 85 90 OUTPUT OUTPUT OUTPUT OUTPUT OUTPUT The input complete event (ICOMP event) is similar to the RCOMP event in that it produces a 1µs pulse for each reading. However, when the ICOMP event is specified, the pulse occurs when the A/D converter has finished integrating the input signal but before the reading is complete (see Figure 20). The ICOMP event can be used with an external scanner when making a single reading per scanner channel.
to assert SRQ (RQS command). The EXTOUT SRQ pulse does not necessarily occur whenever the SRQ bit is set; it occurs whenever an enabled status event occurs. The following program uses the SRQ event to synchronize the multimeter to external equipment. The program downloads a subprogram to the multimeter. When the subprogram is called by the controller (line 120), it configures the multimeter for high-accuracy temperature measurements using a 10k(W) thermistor.
Math Operations Each math operation performs a specific mathematical operation on each reading and/or stores data on a series of readings. The multimeter can perform the null, scale, percent, dB, dBm, filter, RMS, or temperature-related math operations on readings. The statistics and pass/fail math operations do not alter readings but store information pertaining to readings. This section describes how to enable and disable math operations and discusses each math operation in detail. Real-Time vs.
those two operations), send: OUTPUT 722;"MATH CONT" !RE-ENABLES ONE REAL-TIME MATH OPERATION or OUTPUT 722;"MMATH CONT" !RE-ENABLES ONE POST-PROCESS MATH OPERATION To re-enable two previously enabled math operations send: OUTPUT 722;"MATH CONT,CONT" !RE-ENABLES TWO REAL-TIME MATH OPERATIONS or OUTPUT 722;"MMATH CONT,CONT" !RE-ENABLES TWO POST-PROCESS MATH OPERATIONS Math Registers Table 23 shows the registers used by the real-time or post-process math operations.
Result = Reading - OFFSET Where: OFFSET is the value stored in the OFFSET register (typically the first reading). Reading is any reading following the first reading. After you select the NULL operation, the first reading made (real-time) or the first reading taken from memory (post-process) is stored in the OFFSET register. The value of this reading is then subtracted from all subsequent readings.
50 OUTPUT 722;"MMATH NULL" 60 OUTPUT 722;"NRDGS 21" 70 OUTPUT 722;"TRIG SGL" 80 ENTER 722;A READ 90 OUTPUT 722;"SMATH OFFSET,3.05" 100 ENTER 722;Rdgs(*) 105 110 PRINT Rdgs(*) 120 END SCALE !ENABLE POST-PROCESS NULL OPERATION !21 READINGS PER TRIGGER !TRIGGER READINGS !RECALL FIRST READING USING IMPLIED !WRITE 3.
Percent The PERC math operation determines the difference, in percent, between each reading and the value in the PERC register. The equation is: Result = ((Reading - PERC)/PERC)· 100 Where: Reading is any reading. PERC is the value stored in the PERC register (power-on value = 1). You can use the PERC math operation to determine the difference (in percent) between an ideal value and the measured value. For example, the following program determines the percent error of a 10 VDC voltage measurement.
The following program uses the real-time DB operation to determine an amplifier's voltage gain. Line 40 stores the amplifier's input voltage (0.1 V) in the REF register. The amplifier's output voltage is measured and the gain of the amplifier is computed. 10 20 30 40 50 60 70 80 OUTPUT 722;"PRESET NORM" OUTPUT 722;"ACV" OUTPUT 722;"SETACV ANA" OUTPUT 722;"SMATH REF 0.
60 ENTER 722;A 70 PRINT A 80 END !SYN EVENT, ENTER DBM !PRINT DBM For example, if the input voltage is 10V, the power is: 10·log10(102/8/1 mW)= 40.97dBm The following program is similar to the preceding program except that it uses the post-process DBM operation.
operation. That is the readings do not have to be recalled from memory in order to perform the STAT operation. Also notice that the readings must be stored before enabling the post-process STAT operation (if not, the MEMORY ERROR will occur).
10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 165 170 180 190 200 OUTPUT 722;"PRESET NORM" !PRESET,NRDGS 1,AUTO, DCV 10, TRIG SYN OUTPUT 722;"MEM FIFO" !ENABLE READING MEMORY, FIFO MODE OUTPUT 722;"SMATH MIN 9" !LOWER LIMIT = 9(V) OUTPUT 722;"SMATH MAX 11" !UPPER LIMIT = 11(V) OUTPUT 722;"CSB" " !CLEAR STATUS REGISTER OUTPUT 722;"RQS 2 !ENABLE HI/LO STATUS REGISTER BIT OUTPUT 722;"NRDGS 20" !20 READINGS/TRIGGER OUTPUT 722;"TRIG SGL" !TRIGGER READINGS OUTPUT 722;"MMATH PFAIL" !PERFORM POST-PROCESS
For example (using the first equation), if the reading rate is 200Hz and the DEGREE is 20, the time constant is: 1 - -------------------1 t = -------– 1 = 0.092 Seconds 200 ln 20 --------------20 – 1 Using the second equation with the same reading rate and DEGREE produces: t » (1/200) × 20 = 0.1 seconds RMS The RMS math operation can be used to compute the combined RMS value of the AC and DC components of digitized (using the DCV, DSAC, or DSDC command) low frequency signals.
Table 25: Temperature-Related Math Operations MATH Operation Description CTHRM2K Result=temperature (Celsius) of a 2kW thermistor (40653A) CTHRM Result=temperature (Celsius) of a 5kW thermistor (40653B) CTHRM10K Result=temperature (Celsius) of a 10kW thermistor (40653C) FTHRM2K Result=temperature (Fahrenheit) of a 2kW thermistor (40653A) FTHRM Resutt=temperature (Fahrenheit) of a 5kW thermistor (40653B) FTHRM10K Result=temperature (Fahrenheit) of a 10kW thermistor (40653C) CRTD85 Result=tempe
Chapter 5 Digitizing Introduction ......................................................... 129 Digitizing Methods .............................................. 129 The Sampling Rate .............................................. 131 Level Triggering .................................................. 132 Level Triggering Examples ............................ 132 Level Filtering ................................................ 134 DCV Digitizing ....................................................
Chapter 5 Digitizing
Chapter 5 Digitizing Introduction Digitizing is the process of converting a continuous analog signal into a series of discrete samples (readings). Figure 22 shows the result of digitizing a sine wave. This chapter discusses the various ways to digitize signals. The importance of the sampling rate, and how to use level triggering. Note As a supplement to the information in this chapter, Product Note 3458A-2 in Appendix D discusses the trigger and timebase errors that affect digitized measurements.
Table 26: Digitizing Methods Digitizing Method Maximum Sampling Rate Bandwidth Repetitive Signal Required DCV 100 k/sec DC - 15OkHz1 No Direct-Sampling 50 k/sec DC - 12MHz No Sub-Sampling 100 M/sec2 DC - 12MHz Yes 1 Range dependent. See the Specifications in Appendix A for details. Effective sampling rate (refer to "Sub-Sampling" later in this chapter for details). 2 Figure 23. Digitizing signal paths Figure 24.
high-speed mode, the multimeter writes-over any sample still in the output buffer when a new sample is available.) For more information, refer to "The High-Speed Mode" in Chapter 4. The Sampling Rate The Nyquist or Sampling Theorem states: If a continuous, bandwidth-limited signal contains no frequency components higher than F, then the original signal can be recovered without distortion (aliasing) if it is sampled at a rate that is greater than 2F samples per second.
Level Triggering When digitizing, it is important to begin sampling at some defined point on the input signal such as when the signal crosses zero volts or when it reaches the midpoint of its positive or negative peak amplitude. Level triggering allows you to specify when (with respect to voltage and slope) to begin sampling. For example, Figure 26 shows sampling beginning as the input signal crosses 0V with a positive slope. Figure 26.
can select the level triggering shown in Figure 27 merely by specifying the LEVEL trigger event (TRIG LEVEL command). The following program specifies level triggering to occur when the input signal reaches +5V (50% of the 10V range) on a negative slope (AC-coupled). Assuming the input signal has a peak value of 10V and the measurement range is 10V, the result is shown in Figure 27.
this case, a negative percentage of the range (-25%) is used to level trigger at -2.5V. positive slope. Figure 29 shows the result. 10OUTPUT 722;"PRESET DIG" 20OUTPUT 722;"TRIG LEVEL" 30OUTPUT 722;"SLOPE POS" 40OUTPUT 722;"LEVEL - 25, DC" 45!DC coupled 50 END !DCV DIGITIZING, 10V RANGE !LEVEL TRIGGER EVENT !TRIGGER ON POSITIVE SLOPE OF SIGNAL !LEVEL TRIGGER AT -25% OF 10V RANGE Figure 29. Level triggering, -25%, pos.
The PRESET DIG command configures the multimeter for DC voltage measurements with a sampling rate of 50,000 samples per second. PRESET DIG selects a 3µs integration time and level triggering when the input signal crosses zero volts on its positive slope.
max._input Parameter Selects Range Full Scale 0 to .12 100mV 120mV >.12 to 1.2 1V 1.2V >l.2 to 12 10V 12V >12 to 120 100V 120V >120 to 1E3 1000V 1050V • The multimeter’s triggering hierarchy (trigger arm event, trigger event, and sample event) applies to DCV digitizing. Refer to Chapter 4 for more information on the triggering hierarchy. For DCV digitizing, you can use either the TIMER sample event and the NRDGS n,TIMER command: or the SWEEP command.
10OPTION BASE 1 !COMPUTER ARRAY NUMBERING STARTS AT 1 20Num_samples=256 !SPECIFY NUMBER OF SAMPLES 30INTEGER Int_samp(l:256) BUFFER !CREATE INTEGER BUFFER 40ALLOCATE REAL Samp(l:Num_samples) !CREATE REAL ARRAY FOR SAMPLES 50ASSIGN @Dvm TO 722 !ASSIGN MULTIMETER ADDRESS 60ASSIGN @Int_samp TO BUFFER Int_samp(*) !ASSIGN I/O PATH NAME TO BUFFER 70OUTPUT @Dvm;"PRESET DIG" !TARM HOLD, DCV, 10V RANGE, 256 SAMPLES 71 !PER TRIGGER, TIMER SAMPLE EVENT, TIMER INTERVAL = 20µs, TRIG 75 !LEVEL (0%, AC-COUPLED), 3µs INTEG
sampling, the minimum possible interval between samples is 20µs. Figure 30. Direct sampling Direct Sampling Remarks • You cannot use autorange for direct-sampled measurements; you must specify the range as the first parameter of the DSAC or DSDC command (max._input parameter). The max._input parameters and the ranges they select are: Full Scale max._input Parameter Selects Range SINT Format DINT Format 0 to .012 10mV 12mV 50mv >.O12 to .120 100mV 120mV 500mV >.120 to 1.2 1V 1.2V 5.0V >1.
uses whichever command was specified last. (When using the SWEEP command, the sample event is automatically set to TIMER.) • When direct-sampling an input signal with a frequency content ³ 1 MHz, the first sample may be in error because of interpolator settling time. To ensure the first sample is accurate, insert a 500ns delay before the first sample (DELAY 500E-9 command). Direct Sampling Example The following program is an example of DC-couple direct-sampled digitizing.
composite waveform with a period equal to that of the input signal. The advantage of sub-sampling is that samples can be effectively spaced at a minimum interval of 10ns versus 10µs for DCV digitizing and 20µs for direct-sampling. This means that sub-sampling can be used to digitize signals with frequency components up to 12 MHz (the upper bandwidth of the signal path for sub-sampling). Sub-sampled measurements use the track-and-hold circuit, which has a 2 nanosecond aperture.
Figure 31. Sub-sampling example Figure 32. Composite waveform The Sync Source Event In the preceding sub-sampling example, it was assumed that the multimeter could somehow synchronize itself to the periods of the input waveform. This is the function of the sync source event. You can use either the EXT event or the LEVEL event as the sync source event. The EXT sync source event (specified by the SSRC EXT command) occurs on the negative-edge transition on the multimeter’s Ext Trig connector.
Figure 33. Typical synchronizing signal for EXT sync source The LEVEL sync source event (which is the power-on/default sync source event) occurs when the input signal reaches a specified voltage level on the specified slope (level triggering). Figure 31 shows the operation of the LEVEL sync source event (for this example, the LEVEL is specified as 0%, positive slope, AC-coupling). The first sync source event occurs when the input signal crosses 0V with a positive slope.
Sub-Sampling Remarks • For sub-sampling, the trigger event and sample event requirements are ignored (these events are discussed in Chapter 4). The only triggering events that apply to sub-sampling are the trigger arm event (TARM command) and the sync source event (SSRC command). • You cannot use the NRDGS command for sub-sampling. You must use the SWEEP command to specify the number of samples and the effective_interval. The minimum effective_interval for sub-sampling is 10 nanoseconds.
source event and the first sample in each burst; the default delay for sub-sampling is 0 seconds.) Sending Samples to Memory When samples are sent directly to reading memory (MEM FIFO command), the multimeter automatically re-orders the samples producing a composite waveform. For example, in the following program, the sub-sampled data is sent to reading memory using the required SINT memory format. The multimeter places the samples in memory in the corrected order.
the multimeter to take 1000 samples (Num_samples variable) with a 2µs effective_interval (Eff_int variable). The measurement uses the default level triggering for the sync source event (trigger from input signal, 0%. AC-coupling, positive slope). Line 110 generates a SYN event and transfers the samples directly to the computer. Lines 230 through 400 sort the sub-sampled data to produce the composite waveform. The composite waveform is stored in the Wave_form array.
Viewing Sampled Data The program on the following page plots digitized data to the controller’s CRT (this particular program uses sub-sampling and the subroutine Plot_it does the actual plotting). This program is helpful when developing digitizing programs (especially when sub-sampling) since it allows you to see the data being captured.
101!FAST OPERATION, TARM SYN, SUB-SAMPLING (SINT OUTPUT FORMAT), 10V RANGE 102!2ms EFFECTIVE INTERVAL, 1000 SAMPLES 110TRANSFER @Dvm TO @Int_samp;WAIT !SYN EVENT, TRANSFER READINGS 120OUTPUT @Dvm;"ISCALE?" !QUERY SCALE FACTOR FOR SINT FORMAT 130ENTER @Dvm;S !ENTER SCALE FACTOR 140OUTPUT @Dvm;"SSPARM?" !QUERY SUB-SAMPLING PARAMETERS 150ENTER @Dvm;Nl,N2,N3 !ENTER SUB-SAMPLING PARAMETERS 160FOR I=1 TO Num_samples 170 Samp(I)=Int_samp(I) !CONVERT EACH INTEGER READING TO REAL 175 !FORMAT (NECESSARY TO PREVENT PO
670 DRAW Wave_x,Wave_form(Wave_y) 680NEXT Wave_y 690IF Wave_x>l0*Time_div THEN DISP "More samples taken than displayed" 700SUBEND 148 Chapter 5 Digitizing
Chapter 6 Introduction ......................................................... 151 Language Conventions ................................... 152 Command Termination ................................... 152 Multiple Commands ....................................... 152 Parameters ...................................................... 152 Query Commands ........................................... 153 Commands by Functional Group ......................... 155 Commands vs. Measurement Functions ..............
SWEEP ........................................................... 248 T ...................................................................... 251 TARM ............................................................ 251 TBUFF ............................................................ 253 TEMP? ............................................................ 254 TERM ............................................................. 254 TEST .............................................................. 255 TIMER ....
Introduction Chapter 6 Command Reference Introduction The first part of this chapter discusses the multimeter's language. This includes core commands, command termination, parameters, query commands, lists of commands by functional group, and a table relating commands to measurement functions. The remainder of the chapter consists of detailed descriptions of each command (listed in alphabetical order, by command).
Introduction Language Conventions The multimeter communicates with a system controller over the GPIB bus.1 Each instrument connected to GPIB has a unique address. The examples used in this manual are intended for Hewlett-Packard Series 200 or 300 Computers using BASlC language. They assume an GPIB interface select code of 7 and a device address of 22 (factory address setting) resulting in a combined GPIB address of 722. We recommend you retain this address to simplify programming.
Introduction or OUTPUT 722;"ACV 10,-1" From remote only, you can use two commas to indicate a default value. For example, to specify 10 for the first parameter and default the second parameter, send: OUTPUT 722;"ACV 10,," To default the first parameter (which selects autorange in this example) and specify .01 for the second parameter, send: OUTPUT 722; "ACV,,.01" Query Commands A query command ends with a question mark and returns one or more responses to a particular question.
Introduction command specifies integration time in seconds. The range of values for this command is 500ns to 1s. When you send the APER? query command, the multimeter responds with the actual value of integration time presently specified. The QFORMAT (query format) command can be used to specify whether query responses will be numeric (as shown above), alpha, or alphanumeric. For example, the following program changes the query format to ALPHA.
Commands by Functional Group Commands by Functional Group The following is a list of al1 commands recognized by the multimeter categorized by function (measurement functions, digitizing. A/D converter, etc.).
Commands vs. Measurement Functions Commands vs. Measurement Functions Table 6-1 shows the multimeter commands that apply only to certain measurement functions. A bullet (·) indicates the command applies with no restrictions. A number (1 - 5) indicates the command applies with qualifications (see numbered footnotes below the table). A blank indicates the command is not applicable to the measurement function.
ACAL ACAL Autocal. Instructs the multimeter to perform one or all of its self calibrations. Syntax ACAL [type][,security_code] type The type parameter choices are: type Parameter Numeric Query Equiv. Description ALL 0 Performs the DCV, OHMS, and AC autocals DCV 1 DC voltage gain and offset (see first Remark) AC 2 ACV flatness, gain, and offset (see second Remark) OHMS 4 OHMS gain and offset (see third Remark) Power-on type = none. Default type = ALL.
ACBAND • The time required to perform each autocal routine is: ALL DCV AC OHMS : : : : 11 minutes 1 minute 1 minute 10 minutes • Related Commands: CAL, SCAL, SECURE Example OUTPUT 722;"ACAL ALL,3458" !RUNS ALL AUTOCALS USING !FACTORY SECURITY CODE ACBAND AC bandwidth. Specifies the frequency content (bandwidth) of the input signal for all AC or AC+DC measurements. Specifying the bandwidth allows the multimeter to configure for the fastest possible measurements.
ACDCI, ACDCV, ACI, ACV ACBAND parameters. • Query Command. The ACBAND? query command returns two numbers separated by a comma. The first number is the currently specified low_frequency, the second number is the high_frequency. Refer to "Query Commands" near the front of this chapter for more information. • Related Commands: ACDCI, ACDCV, ACI, ACV, FREQ, FUNC, PER.
APER APER Aperture. Specifies the A/D converter integration time in seconds. Syntax APER [aperture] aperture Specifies the A/D converter's integration time and overrides any previously specified integration time or resolution. The valid range for aperture is 0 - 1s in increments of 100ns. (Specifying a value <500ns selects minimum aperture which is 500ns.) Power-on aperture = is determined by the power-on value for NPLC which specifies an integration time of 166.
AUXERR? control Parameter Numeric Query Equiv. Description OFF 0 Disables autorange algorithm ON 1 Enables autorange algorithm ONCE 2 Causes the multimeter to autorange once, then disables autoranging Power-on control = ON. Default control = ON. Remarks • With autorange enabled, the multimeter samples the input signal before each reading and selects the appropriate range. • Refer to the FUNC or RANGE command for a listing of the ranges for each measurement function.
AZERO Remarks Weighte d Value Bit Number Description 16 4 A/D converter convergence failure 32 5 Calibration value out of range 64 6 GPIB chip failure 128 7 UART failure 256 8 Timer failure 512 9 Internal overload 1024 10 ROM checksum failure, low-order byte 2048 11 ROM checksum failure, high-order byte 4096 12 Nonvolatile RAM failure 8192 13 Option RAM failure 16384 14 Cal RAM write or protection failure • The auxiliary error register indicates hardware related errors.
AZERO control The control parameter choices are: Control Parameter Numeric Query Equiv. OFF 0 Zero measurement is updated once, then only after a function, range, aperture, NPLC, or resolution change. ON 1 Zero measurement is updated after every measurement. ONCE 2 Zero measurement is updated once, then only after a function, range, aperture, NPLC, or resolution change.
BEEP BEEP Controls the multimeter's beeper. When enabled, the beeper emits a 1 kHz beep if an error occurs. Syntax BEEP [control] control The control parameter choices are: control Parameter Numeric Query Equiv. Description OFF 0 Disables the beeper ON 1 Enables the beeper ONCE 2 Beeps once, then returns to previous mode (either OFF or ON) Power-on control = last programmed value. Default control = ONCE.
CALNUM? Default name = 0. Remarks • Subprograms are created with the SUB command. • The multimeter sets bit 0 in the status register after executing a stored subprogram. • From the front panel, you can view all stored subprogram names by accessing the CALL command and pressing the up or down arrow key. Once you have found the correct subprogram, press the Enter key to execute the subprogram.
COMPRESS Syntax CALSTR string[,security_code] string This is the alpha/numeric message that will be appended to the calibration RAM. The string parameter must be enclosed in single or double quotes. The maximum string length is 75 characters (the quotes enclosing the string are not counted as characters). security_code When the calibration RAM is secured (SECURE command) you must include the security_code in order to write a message to the calibration RAM.
CONT • Related Commands: CALL, CONT, DELSUB, PAUSE, SCRATCH, SUB, SUBEND Example The following program statement compresses subprogram TEST12 (previously downloaded). OUTPUT 722;"COMPRESS TEST12" CONT Continue. Resumes execution of a subprogram that has been suspended by a PAUSE command. Syntax CONT Remarks • The GPIB Group Execute Trigger function may also be used to resume execution of a suspended subprogram. • Only one subprogram will be preserved in a suspended state.
DCI, DCV DCI, DCV Refer to the FUNC command. DEFEAT Enables or disables the multimeter's input protection algorithm (see CAUTION below) and some syntax and error checking algorithms. With these algorithms disabled, the multimeter can change to a new measurement configuration faster than it can with them enabled. Syntax DEFEAT [mode] mode The mode parameter choices are: mode Parameter Numeric Query Equiv.
DEFKEY Example OUTPUT 722;"DEFEAT ON" !DISABLES PROTECTION, SYNTAX & ERROR ALGORITHMS DEFKEY Define Key. Allows you to assign one or more commands to a particular user-defined function key on the front panel (these keys are labeled f0 - f9). After assigning one or more commands to a key, pressing that key displays the command(s) on the multimeter's display. Pressing the Enter key will then execute the command(s) in the order listed.
DELAY Examples DEFKEY OUTPUT 722;"DEFKEY 1,'DCI 1;AZERO 0FF;NPLC 0'" !ASSIGNS COMMANDS TO F1 Clearing All DEFKEYs OUTPUT 722;"DEFKEY DEFAULT" !CLEARS ALL DEFKEYS DEFKEY? 10 OUTPUT 722;"DEFKEY? 1" !RETURNS DEFINITION FOR KEY 1 20 ENTER 722;A$ !ENTERS DEFINITION INTO A$ VARIABLE 30 PRINT A$ !PRINTS DEFINITION 40 END A typical response returned by the above program is: "DCI 1;AZERO OFF;NPLC 0." If nothing is assigned to DEFKEY 1, the above program returns: “DEFKEY F1.
DELSUB DELSUB Delete Subprogram. Removes a single subprogram from memory. Syntax DELSUB name name Subprogram name. A subprogram name may contain up to 10 characters. The name can be alpha, alphanumeric, or an integer in the range of 0 to 127. Refer to the SUB command for details. Power-on name = none. Default name = none; parameter required. Remarks • When a subprogram is deleted, the memory used to store it is freed and may be used to store a new subprogram (see the SUB command).
DSAC, DSDC Power-on control = ON. Default control = ON. message The message parameter is the message to be displayed. The message may contain spaces, numerals, lower or upper case letters, and any of the following characters: !#$ Remarks %&'()^\/@;:[],.+-=*<>?_ • You must enclose a message in quotation marks only if it contains a space, comma, or semicolon. Either single or double marks (' or ") may be used: the beginning and ending marks must match.
DSAC, DSDC following table shows the max._input parameters and the ranges they select. Full Scale max._put Parameter Selects Range SINT Format DINT Format 0 to .012 10mV 12mV 50mV >.012 to .120 100mV 120mV 500mV >.120 to 1.2 1V 1.2V 5.0V >1.2 to 12 10V 12V 50V >12 to 120 100V 120V 500V >120 to 1E3 1000V 1050V 1050V Power-on max._input= not applicable. Default max._input = 10V. %_resolution Is ignored by the multimeter when used with the DSAC or DSDC command.
EMASK memory/output format, no format conversions are necessary.) • Related Commands: DSDC, FUNC, LEVEL, LFILTER, SLOPE, NRDGS, PRESET FAST, PRESET DIG, SSAC, SSDC, SSPARM?, SWEEP, TARM, TIMER, TRIG Example The following program is an example of DC-coupled, direct-sampled digitizing. The SWEEP command specifies an interval of 30µs and 200 samples. Level triggering is set for 250% of the 10V range (250% of 10V = 25V). The samples are sent to reading memory in DINT format.
EMASK weights.
END END The END command enables or disables the GPIB End Or Identify (EOI) function. Syntax END [control] control The control parameter choices are: control Parameter Numeric Query Equiv. Description OFF 0 EOI line never set true ON 1 For multiple readings (SWEEP or NRDGS >1) the EOI line is set true with the last byte of the last reading sent. For single readings, EOI line set true with the last byte of each reading. ALWAYS 2 EOI line set true when the last byte of each reading sent.
ERR? ERR? Error Query. When an error occurs, it sets a bit in the error register and illuminates the display's ERR annunciator. The ERR? command returns a number representing all set bits, clears the register, and shuts off the annunciator. The returned number is the weighted sum of all set bits.
ERRSTR? 30 PRINT A !PRINTS RESPONSE 40 END ERRSTR? Error String Query. The ERRSTR? command reads the least significant set bit in either the error register or the auxiliary error register and then clears the bit. The ERRSTR? command returns two responses separated by a comma. The first response is an error number (100 series = error register; 200 series = auxiliary error register) and the second response is a message (string) explaining the error.
EXTOUT event The event choices are: event Parameter Numeric Query Equiv.
FIXEDZ • Related Commands: NRDGS, SRQ, STB?, SWEEP, TBUFF Example OUTPUT 722;"EXTOUT APER" !SETS EXTOUT EVENT TO APERTURE WAVEFORM FIXEDZ The FIXEDZ command enables or disables the fixed input resistance function for DC voltage measurements. When enabled, the multimeter maintains its input resistance at 10 megohms for all ranges. This prevents a change in input resistance (caused by a range change) from affecting the DC voltage measurements.
FREQ FREQ Frequency. Instructs the multimeter to measure the frequency of the input signal. You must specify whether the input signal is AC voltage, AC+DC voltage, AC current, or AC+DC current using the FSOURCE command. Syntax FREQ [max._input][,%_resolution] max._input Selects a fixed range or the autorange mode. The ranges correspond to the type of input signal specified in the FSOURCE command. That is, if ACV is the specified input signal, the max.
FSOURCE • The leftmost digit which is a half digit for most measurement functions, is a full digit (0 - 9) for frequency measurements. • Readings made with autorange enabled take longer because the input signal is sampled (to determine the proper range) between frequency readings. • For frequency (and period) measurements, an overload indication means the voltage or current amplitude is too great for the specified measurement range.
FUNC FUNC Function. Selects the type of measurement (AC voltage, DC current. etc.). lt also allows you to specify the measurement range and resolution. (The FUNC header is optional and may be omitted.) Syntax FUNC [function][,max._input][,%_resolution] or [FUNC] function[,max._input][,%_resolution] function The function parameter designates the type of measurement. The parameter choices are: function Parameter Numeric Query Equiv.
FUNC To select autorange, specify AUTO for max._input or default the parameter. In the autorange mode, the multimeter samples the input signal before each reading and selects the appropriate range. • The following tables show the max._input parameters and the ranges they select for each measurement function. For DCV: For DCI: max._input Parameter Selects Range Full Scale –1 or AUTO 0 to .12 >.12 to 1.2 >1.2 to 12 >12 to 120 >120 to 1E3 Autorange 100mV 1V 10V 100V 1000V 120mV 1.
FUNC %_resolution For most measurement functions, you specify the %_resolution as a percentage of the max._input parameter. (Refer to the FREQ and PER commands for tables showing how %_resolution affects frequency and period measurements; %_resolution is ignored when the function parameter is DSAC, DSDC, SSAC, or SSDC.) For all functions except FREQ, PER, DSAC, DSDC, SSAC, and SSDC, the multimeter multiplies %_resolution times max._input to determine the measurement's resolution.
ID? Examples In the following program, line 10 allows %_resolution in line 20 to control the resolution. The resolution specified by line 20 is 6V × .0000167 = 100µV. 10 OUTPUT 722;"NPLC 0" !SETS PLCS TO MINIMUM 20 OUTPUT 722;"FUNC DCV,6,.00167" !SELECTS DC VOLTS, 6V MAX, 30 END !100µV RESOLUTION In the following program, line 10 sets the number of PLCs to 1000. This corresponds to maximum resolution (7.5 digits) and prevents %_resolution in line 20 from affecting the measurement.
ISCALE? control The control parameter choices are: control Parameter Numeric Query Equiv. OFF 0 Disables the input buffer; commands are accepted only when the multimeter is not busy ON 1 Enables the input buffer; commands are stored, releasing the bus immediately Description Power-on control = OFF. Default control = ON. Remarks • Turning the input buffer OFF causes a minor degradation in speed performance, but is useful for synchronizing bus activity.
ISCALE? Syntax ISCALE? Remarks • The scale factor is always 1 for the ASCII, SREAL, and DREAL output formats. • Readings output in the SINT or DINT formats (see the OFORMAT command) are first compressed by the multimeter so they may be expressed as integers. Multiplying the readings by the value returned by ISCALE? will restore them to their actual values. The scale factor is determined by the configuration of the multimeter when ISCALE? is executed.
LEVEL 30 Num_readings=50 !NUMBER OF READINGS = 50 40 ALLOCATE REAL Rdgs(l:Num_readings) !CREATE ARRAY FOR READINGS 50 ASSIGN @Dvm TO 722 !ASSIGN MULTIMETER ADDRESS 60 ASSIGN @Buffer TO BUFFER[4*Num_readingsl!ASSIGN BUFFER I/O PATH NAME 70 OUTPUT @Dvm;"PRESET NORM;RANGE 10;OFORMAT DINT;NRDGS ";Num_readings 75 !TARM AUTO, TRIG SYN, DCV 10V RANGE, DINT OUTPUT FORMAT, NRDGS 50,AUTO 80 TRANSFER @Dvm TO @Buffer;WAIT!SYN EVENT,TRANSFER READINGS 90 OUTPUT @Dvm; "ISCALE?" !QUERY SCALE FOR DINT 100 ENTER @Dvm;S
LFILTER circuitry only. This does not affect the coupling of the signal being measured. coupling Parameter Numeric Query Equiv. DC 1 Selects DC-coupled input to level-detection circuitry AC 2 Selects AC-coupled input to level-detection circuitry Description Power-on coupling = AC. Default coupling = AC. Remarks • Level triggering can be used for DC voltage, direct-sampling, and sub-sampling.
LFREQ Syntax LFILTER [control] control The control parameter choices are: control parameter Numeric Query Equiv. Description OFF 0 Disables the level filter; no filtering is done ON 1 Enables the level filter Power-on control = OFF. Default control = ON. Remarks • Level filtering can be used when level triggering for DC voltage, direct- and sub-sampling.
LINE? Default reference frequency = the exact measured line frequency (or measured value/8 for 400Hz line frequency). LINE Measures the exact value of the line frequency and sets the reference frequency to that value (or measured value/8 if the measured value is between 360 and 440Hz). Remarks • When power is applied, the multimeter measures the line frequency, rounds it to 50 or 60Hz, and sets the A/D Converter's reference frequency to the rounded value.
LOCK reference frequency to the measured value. • Related Commands: LFREQ 10 OUTPUT 722; "LINE?" !MEASURES THE LINE FREQUENCY 20 ENTER 722;A !ENTERS RESPONSE INTO COMPUTER'S A VARIABLE 30 PRINT A !PRINTS RESPONSE 40 END LOCK Lockout. Enables or disables the multimeter's keyboard Syntax LOCK [control] control The control parameter choices are: control Parameter Numeric Query Equiv.
MATH operation The operation parameter choices are: 194 operation Parameter Numeric Equiv. Description OFF 0 Disables all enabled real-time math operations CONT 1 Enables the previous math operation. To resume two math operations, send MATH CONT,CONT CTHRM 3 Result=temperature (Celsius) of a 5kW thermistor (40653B). Function must be OHM or OHMF (10kW range or higher). DB 4 Result = 20 x Log10(reading/REF register). The REF register is initialized to 1, yielding dBV.
MATH operation Parameter Numeric Equiv. CRTD85 20 Result=temperature (Celsius) of 100W RTD with alpha of 0.00385 (40654A or 406548). Function must be OHM or OHMF. CRTD92 21 Result=temperature (Celsius) of 100W RTD with alpha of 0.003916. Function must be OHM or OHMF. FRTD85 22 Result=temperature (Fahrenheit) of 100W RTD with alpha of 0.00385 (40654A or 406548). Function must be OHM or OHMF. FRTD92 23 Result=temperature (Fahrenheit) of 100W RTD with alpha of 0.003916.
MCOUNT? Example The following program performs the real-time NULL math operation on 20 readings. After executing the NULL command, the first reading is triggered by line 50. The value in the OFFSET register is then changed to 3.05. The 20 read-ings are triggered by line 90 and 3.05 is subtracted from each reading.
MENU mode Parameter Numeric Query Equiv. FIFO 2 Clears reading memory and stores new readings FIFO (first-in-first-out) CONT 3 Keeps memory intact and selects previous mode (if there was no previous mode, FIFO is selected) Description Power-on mode = OFF. Default mode = ON. Remarks • In the high-speed mode, when reading memory is enabled in the FIFO mode and becomes full, the trigger arm event becomes HOLD which stops readings and removes the multimeter from the high-speed mode.
MFORMAT Syntax MENU [mode] mode The mode parameter choices are: mode Parameter Numeric Query Equiv. Description SHORT 0 Selects the short command menu FULL 1 Selects the full command menu Power-on mode = mode selected when power was removed. Default mode = FULL Remarks • To access the alphabetic command menu, press any of the shifted MENU keys labeled C, E, L, N, R, S, and T. You can then locate a particular command using the up and down arrow keys.
MFORMAT The format parameter choices are: format Parameter Numeric Query Equiv.
MMATH FIFO (MEM FIFO command), and reading memory must be empty (done by executing the MEM FIFO command) before samples are taken. If these requirements are not met when the trigger arm event occurs, an error is generated. • Query Command. The MFORMAT? query command returns the present memory format. Refer to "Query Commands" near the front of this chapter for more information.
MMATH operation Parameter Numeric Equiv. FTHRM 8 Result=temperature (Fahrenheit) of a 5kW thermistor (40653B). Function must be OHM or OHMF (10kW) range or higher). NULL 9 Result=reading-OFFSET register. The OFFSET register is set to first reading—after that you can change it. PERC 10 Result =((reading - PERC register) / PERC register) x 100. PFAIL 11 Reading vs. MAX and MIN registers. RMS 12 Result = squares reading, applies FILTER operation, takes square root.
MMATH Power-on register values = a11 registers are set to 0 with the following exceptions: DEGREE = 20 REF = 1 SCALE = 1 RES = 50 PERC = 1 Remarks • Any enabled post-process math operations except STAT and PFAIL are performed on each reading as it is removed or copied from reading memory to the display or the GPIB output buffer. (The readings in memory are not altered by any post-process math operation.
MSIZE • When you use the RMEM command to recall readings, it turns off reading memory. This means any new readings will not be placed in reading memory and cannot have an enabled memory math operation performed on them. When you use the "implied read" method to recall readings, reading memory is not turned-off. • Related Commands: MATH, MEM, RMATH, RMEM, SMATH Example The following program performs the post-process NULL operation on 20 readings.
NDIG • Query Command. The MSIZE? query command returns two responses separated by a comma. The first response is the total number of bytes of reading memory. The second response is the largest block (in bytes) of unused subprogram/state memory. • Related Commands: MCOUNT?, MEM, MFORMAT, RMEM, DELSUB, SCRATCH, SUB, SUBEND, SSTATE Example 10 OUTPUT 722; "MSIZE?" !QUERY MEMORY SIZES 20 ENTER 722;A,B !ENTER RESPONSES 30 PRINT A,B !PRINT RESPONSES 40 END NDIG Number of Digits.
NPLC Syntax NPLC [power_line_cycles] power_line_cycles The primary use of the NPLC command is to establish normal mode noise rejection (NMR) at the A/D converter's reference frequency (LFREQ command). Any value ³1 for the power_line_cycles parameter provides at least 60 dB of NMR at the power line frequency. Any value <1 provides no NMR; it only sets the integration time for the A/D converter. The ranges and the incremental step sizes for the power_line_cycles parameter are: 0 - 1 PLC in .
NRDGS interaction occurs between NPLC (or APER) when you specify resolution as follows: • If you send the NPLC (or APER) command before specifying resolution, the multimeter satisfies the command that specifies greater resolution (more integration time). • If you send the NPLC (or APER) command after specifying resolution, the multimeter uses the integration time specified by the NPLC (or APER) command, and any previously specified resolution is ignored.
NRDGS Designates the number of readings per trigger event. The valid range for this parameter is 1 to 16777215. (The count parameter also corresponds to the record parameter in the RMEM command. Refer to the RMEM command for details.) Power-on count = 1. Default count = 1. event Designates the event that initiates each reading (sample event). The event parameter choices are: event Parameter Numeric Query Equiv.
NRDGS events, a single occurrence of the SYN event satisfies all of the specified SYN event requirements. This is shown in the second "SYN Event" example below. • Query Command. The NRDGS? query command returns two responses separated by a comma. The first response is the specified number of readings per trigger. The second response is the present sample event. Refer to "Query Commands" near the front of this chapter for more information.
OCOMP 50 OUTPUT 722;"NRDGS 4,TIMER" !SELECTS 4 READINGS/TRIGGER & TIMER 60 ENTER 722;Rdgs(*) !TRIGGER AND ENTER READINGS 70 PRINT Rdgs(*) !PRINT READINGS 80 END OCOMP The OCOMP command enables or disables the offset compensated ohms function. Syntax OCOMP [control] control The control parameter choices are: control Parameter Numeric Query Equiv. Description OFF 0 Offset compensated ohms disabled. ON 1 Offset compensated ohms enabled. Power-on control = OFF. Default control = ON.
OFORMAT OFORMAT Output Format. Designates the GPIB output format for readings sent directly to the controller or transferred from reading memory to the controller. Syntax OFORMAT [format] format The format parameter choices are: format Parameter Numeric Query Equiv.
OFORMAT SINT format: +32767 or -32768 (unscaled) DINT format: +2.147483647E+9 or -2.147483648E+9 (unscaled) ASCII, SREAL, DREAL: +/-1.OE+38 • When reading memory is disabled, executing the SSAC or SSDC command(sub-sampling) automatically sets the output format to SINT regardless of the previously specified format. You must use the SINT output format when sub-sampling and not using reading memory. • The output format applies only to readings transferred over the GPIB bus.
OFORMAT 120 FOR I=1 TO Num_readings 130 Rdgs(I)=Int_rdgs(I) !CONVERT EACH INTEGER READING TO REAL 135 !FORMAT (NECESSARY TO PREVENT POSSIBLE INTEGER OVERFLOW ON NEXT LINE) 140 R=ABS(Rdgs(I)) !USE ABSOLUTE VALUE TO CHECK FOR OVLD 150 IF R>=32767 THEN PRINT "OVLD" !IF OVLD, PRINT OVERLOAD MESSAGE 160 Rdgs(I)=Rdgs(I)*S !MULTIPLY READING TIMES SCALE FACTOR 170 Rdgs(I)=DROUND(Rdgs(I),4) !ROUND TO 4 DIGITS 180 NEXT I 190 END DINT Format The following program is similar to the preceding program except tha
OFORMAT 70 OUTPUT @Dvm;"PRESET NORM;OFORMAT SREAL;NRDGS ";Num_readings 75 !TRIG SYN, SREAL OUTPUT FORMAT, 1 PLC, DCV AUTORANGE, 10 READINGS 80 TRANSFER @Dvm TO @Buffer;WAIT !SYN EVENT; TRANSFER READINGS 90 FOR I=1 TO Num_readings 100 ENTER @Buffer USING "#,B";A,B,C,D!ENTER ONE 8-BIT BYTE INTO 101 !EACH VARIABLE, (# =STATEMENT TERMINATION NOT REQUIRED, B = ENTER ONE 105 !8-BIT BYTE AND INTERPRET AS AN INTEGER BETWEEN 0 AND 255) 110 S=1 !CONVERT READING FROM SREAL 120 IF A>127 THEN S=-1 !CONVERT READING
OHM, OHMF The preceding program used the TRANSFER statement to get readings from the multimeter. The following program uses the ENTER statement to transfer readings to the computer using the DREAL format. The ENTER statement is easier to use since no I/O path is necessary but is much slower than the TRANSFER statement. Also when using the ENTER statement, you must use the FORMAT OFF command to instruct the controller to use its internal data structure instead of ASCII.
PAUSE PAUSE Suspends subprogram execution. The subprogram can be resumed using the CONT command or by executing the GPIB Group Execute Trigger command. Syntax PAUSE Remarks • The PAUSE command is allowed only within a subprogram. • Only one subprogram will be preserved in a suspended state. If a subprogram is paused and another is run which also becomes paused, the first will be terminated and the second will remain suspended.
PER When the subprogram is finished, a total of 15 readings are in memory. To call the above subprogram, send: OUTPUT 722;"CALL OHMAC1" After the five 2-wire ohms readings are complete, connect an AC voltage source to the multimeter. Subprogram execution is resumed by sending the CONT command or by executing (on the controller): TRIGGER 7 PER Period. Instructs the multimeter to measure the period of the input signal.
PRESET Power-on %_resolution = not applicable. Default %_resolution = .00001. Remarks • The reading rate is the longer of 1 period of the input signal, the gate time, or the default reading time-out of 1.2 seconds. • Period (and frequency) measurements are made using the level detection circuitry to determine when the input signal crosses a particular voltage on its positive or negative slope.
PRESET AZERO ON MFORMAT SREAL BEEP ON MMATH OFF DCV AUTO NDIG 6 DELAY -1 NPLC 1 DISP ON NRDGS 1,AUTO FIXEDZ OFF OCOMP OFF FSOURCE ACV OFORMAT ASCII INBUF OFF TARM AUTO LOCK OFF TIMER 1 MATH OFF TRIG SYN All math registers set to 0 except: DEGREE = 20 PERC = 1 REF = 1 RES = 50 SCALE = 1 FAST PRESET FAST configures the multimeter for fast readings, fast transfer to memory, and fast transfer from memory to GPIB.
PURGE OFORMAT SINT Remarks Examples • Related Commands: RESET OUTPUT 722;"PRESET NORM" !CONFIGURES FOR REMOTE OPERATION OUTPUT 722;"PRESET FAST" !CONFIGURES FOR FAST READINGS/TRANSFER OUTPUT 722;"PRESET DIG" !CONFIGURES FOR FAST DCV DIGITIZING PURGE Purge State. Removes a single stored state from memory. Syntax PURGE name name State name. A state name may contain up to 10 characters. The name can be alpha, alphanumeric, or an integer in the range of 0 to 127.
QFORMAT type Parameter Numeric Query Equiv. NORM 1 ALPHA Description Query responses sent to the GPIB are numeric only (whenever possible) with no headers; query responses sent to the display contain alpha headers and alpha responses (whenever possible) Query responses sent to either GPIB or the display contain an alpha header and an alpha response (whenever possible) Power-on type = NORM. Default type = NORM.
R ALPHA 10 OUTPUT 722; "QFORMAT ALPHA" 20 OUTPUT 722; "ARANGE?" 30 ENTER 722;A$ 40 PRINT A$ 50 END Typical response: ARANGE ON R R is an abbreviation for the RANGE command. Syntax R [max._input][,%_resolution] Refer to the RANGE command for more information. RANGE The RANGE command allows you to select a measurement range or the autorange mode. Syntax RANGE [max._input][,%_resolution] max._input The max._input parameter selects a fixed range or the autorange mode.
RANGE For DCV: For DCI: max._input Parameter Selects Range Full Scale –1 or AUTO 0 to .12 >.12 to 1.2 >1.2 to 12 >12 to 120 >120 to 1E3 Autorange 100mV 1V 10V 100V 1000V 120mV 1.2V 12V 120V 1050V max._input Parameter Selects Range Full Scale –1 or AUTO 0 to .012 >.012 to .12 >.12 to 1.2 >1.2 to 12 >12 to 120 >120 to 1E3 Autorange 10mV 100mV 1V 10V 100V 1000V 12mV 120mV 1.2V 12V 120V 1050V max.
RANGE frequency and period measurements, you specify %_resolution as the number of digits to be resolved. For the remaining measurement functions (DCV, ACV, ACDCV, OHM, OHMF, DCI, and ACI), you specify the %_resolution as a percentage of the max._input parameter. The multimeter then multiplies %_resolution by the max._input to determine the measurement's resolution. For example, suppose your maximum expected input is 10V and you want 1mV of resolution.
RATIO Chapter 0:Command Reference RATIO The RATIO command instructs the multimeter to measure a DC reference voltage applied to the W Sense terminals and a signal voltage applied to the Input terminals. The multimeter then computes the ratio as: Ratio = Signal Voltage DC Reference Voltage Syntax RATIO [control] control control Parameter Numeric Query Equiv.
RES 60 ENTER 722;A !ENTER RATIO 70 PRINT A !PRINT RATIO 80 END RES Resolution. Specifies reading resolution. Syntax RES [%_resolution] %_resolution For frequency and period measurements, the %_resolution parameter specifies the digits of resolution and the gate time as shown below. (%_resolution also affects the reading rate. Refer to the Specifications in Appendix A for more information.) If you default the %_resolution parameter for frequency or period measurements, the multimeter uses .00001.
RESET For frequency or period measurements, the defau1t %_resolution is .00001 which selects a gate time of 1s and 7 digits of resolution. For sampled ACV or ACDCV, the default %_resolution is 0.01% for SETACV SYNC or 0.4% for SETACV RNDM. For all other measurement functions, the default resolution is determined by the present integration time.
RESET Aborts readings in process. Clears error and auxiliary error registers. Clears the status register except the Power-on SRQ bit (bit 3). Clears reading memory.
REV? 30 END REV? Revision Query. Returns two numbers separated by a comma. The first number is the multimeter's master processor firmware revision. The second number is the slave processor firmware revision. Syntax REV? Example 10 OUTPUT 722; "REV?" !READ FIRMWARE REVISION NUMBERS 20 ENTER 722; A, B !ENTER NUMBERS 30 PRINT A, B !PRINT NUMBERS 40 END RMATH Recall Math. Reads and returns the contents of a math register.
RMEM register Parameter Numeric Query Equiv. PFAILNUM 15 Register Contents The number of reading that passed PFAIL before a failure was encountered Power-on register = none. Default register = DEGREE. Remarks • Math register contents are always output in the ASCII output format regardless of the specified output format. Afterwards, the output format returns to that previously specified (SINT, DINT, SREAL, DREAL, or ASCII).
RQS Designates the record from which to recall readings. Records correspond to the number of readings specified by the NRDGS command. For example, if NRDGS specifies three readings per trigger, each record will contain three readings. Power-on record = none. Default record = 1. Remarks • The RMEM command automatically shuts off reading memory (MEM OFF). This means all previously stored readings remain intact and new readings are not stored.
RSTATE You enable a condition by specifying its decimal weight as the value parameter. For more than one condition, specify the sum of the weights.
SCAL Power-on name = none. Default name = 0. Remarks • Whenever the multimeter's power is removed, the present state is stored in state 0. After a power failure, the multimeter can be configured to its previous state by executing RSTATE 0. • If the NULL real-time math operation was enabled in a stored state, after recalling the state, the first reading is placed in the OFFSET register (refer to "NULL" in Chapter 4 for more information).
SETACV the factory with its security code set to 3458. new_code This is the new security code. The code is an integer from -2.1E9 to 2.1E9. If the number specified is not an integer, the multimeter rounds it to an integer value. acal_secure Allows you to secure autocalibration. The choices are: acal_secure Parameter Numeric Query Equiv. OFF 0 Disables autocal security; no code required for autocal ON 1 Enables autocal security; the security code is required to perform autocal (see ACAL for example).
SLOPE sampling, or synchronous sampling. The parameters are: type Parameter Numeric Query Equiv. Description ANA 1 Analog RMS conversion RNDM 2 Random sampling conversion SYNC 3 Synchronous sampling conversion Power-on type = ANA. Default type = ANA. Remarks • Bandwidth limitations vary with the conversion technique selected. See the Specifications in Appendix A for details. • Query Command. The SETACV? query command returns the present AC measurement method.
SMATH Refer to "Query Commands" near the front of this chapter for more information. • Related Commands: LEVEL, LFILTER, NRDGS, SSRC, TRlG Example OUTPUT 722;"SLOPE POS" !LEVEL DETECTION !SELECTS THE POSITIVE GOING SLOPE FOR SMATH Store Math. Places a number in a math register. Syntax SMATH [register][,number] register The registers that can be written to are: register Parameter Numeric Query Equiv.
SRQ The number parameter is the value to be placed in the register. Default number = last reading. Power-on number = see above listing. Remarks • You can use the SMATH command to place a number into one of the registers that store readings (UPPER, LOWER, etc.); however, that value will be replaced with a reading if the corresponding math function is enabled (e.g. STATS). • You cannot use -1 (minus 1) to default the number parameter. If you specify -1, you will actually write -1 to the register.
SSAC, SSDC SSAC, SSDC Sub-Sampling. Configures the multimeter for sub-sampled voltage measurements (digitizing). The SSAC function measures only the AC component of the input waveform. The SSDC function measures the combined AC and DC components of the waveform. Otherwise, the two functions are identical. The input signal must be periodic (repetitive) for sub-sampled measurements. Sub-sampled measurements use the track/hold circuit (2 nanoseconds aperture) and a wide bandwidth input.
SSAC, SSDC is not changed). Later, where you change to another measurement function, the output format returns to that previously specified. You must use the SINT output format when sub-sampling and outputting samples directly to the GPIB. You can, however, use any output format if the samples are first placed in reading memory (see next remark).
SSAC, SSDC 90 OUTPUT @Dvm; "SSDC 10" !SUB-SAMPLING, 10V RANGE, DC-COUPLED 100 OUTPUT @Dvm; "SWEEP 5E - 6,200"!5µs EFF.
SSPARM? 220 Samp(I)=DROUND(Samp(I),4) !ROUND TO 4 DIGITS 230 NEXT I 235 !--------------------------SORT SAMPLES-----------------------------240 Inc=N1+N2 !TOTAL NUMBER OF BURSTS 250 K=1 260 FOR I=1 TO N1 270 L=I 280 FOR J=1 TO N3 290 Wave_form(L)=Samp(K) 300 K=K+1 310 L=L+Inc 320 NEXT J 330 NEXT I 340 FOR I=N1+l TO N1+N2 350 L=I 360 FOR J=1 TO N3-1 370 Wave_form(L)=Samp(K) 380 K=K+ 1 390 L=L+Inc 400 NEXT J 410 NEXT I 420 END SSPARM? Sub-Sampling Parameters Query.
SSRC command allows you to synchronize bursts to an external signal or to a voltage level on the input signal. For synchronous ACV or ACDCV (SETACV SYNC command), the SSRC command allows you to synchronize sampling to an external signal. You can also use the HOLD parameter to prevent the measurement method from changing to random should level triggering not occur within certain time limits. The time limits are determined by the AC bandwidth (ACBAND command) setting.
SSRC Power-on mode = AUTO Default mode = AUTO Remarks • For sub-sampling, the trigger event and the sample event are ignored. The only triggering events that apply to sub-sampling are the trigger arm event (TARM command) and the sync source event (SSRC command).
SSRC 130 OUTPUT @Dvm;"ISCALE?" !QUERY SCALE FACTOR FOR SINT FORMAT 140 ENTER @Dvm; S !ENTER SCALE FACTOR 150 OUTPUT @Dvm;"SSPARM?" !QUERY SUB-SAMPLING PARAMETERS 160 ENTER @Dvm;N1,N2,N3 !ENTER SUB-SAMPLING PARAMETERS 170 FOR I=1 TO Num_samples 180 Samp(I)=Int_samp(I) !CONVERT EACH INTEGER READING TO REAL 190 !FORMAT (NECESSARY TO PREVENT POSSIBLE INTEGER OVERFLOW ON NEXT LINE) 190 R=ABS(Samp(I)) !USE ABSOLUTE VALUE TO CHECK FOR OVLD 200 IF R>=32767 THEN PRINT "OVLD" !IF OVLD, PRINT OVERLOAD MESS
SSTATE SSTATE Store State. Stores the multimeter's present state and assigns it a name. States are recalled using the RSTATE command. Syntax SSTATE name name State name. A state name may contain up to 10 characters. The name can be alpha, alphanumeric, or an integer in the range of 0 to 127. When using an alphanumeric name, the first character must be alpha. Alpha or alphanumeric state names must not be the same as multimeter commands or parameters or the name of a stored subprogram.
STB? found the desired state, press the Enter key to recall that state. • Related Commands: MSIZE, PURGE, RSTATE, SCRATCH Example OUTPUT 722;"SSTATE B2 " !STORES PRESENT STATE WITH NAME B2 STB? Status Byte Query. The status register contains seven bits that monitor various multimeter conditions. When a condition occurs, the corresponding bit is set in the status register. The STB? (status byte?) command returns a number representing the set bits. The returned number is the weighted sum of all set bits.
SUB SUB Subprogram. Stores a series of commands as a subprogram and assigns the sub-program name. Syntax SUB name name Subprogram name. A subprogram name may contain up to 10 characters. The name can be alpha, alphanumeric, or an integer from 0 to 127. When using an alphanumeric name, the first character must be alpha. Alpha or alphanumeric subprogram names must not be the same as multimeter commands or parameters or the name of a stored state.
SUB • The only way to take readings within a subprogram is to use the TARM SGL or TRIG SGL command. When either of these commands is encountered, the multimeter will not execute the next command in the subprogram until all specified readings are taken. (This also means all configuration and other triggering commands must occur before the TARM SGL or TRIG SGL command.
SUBEND until another external trigger occurs. After the external trigger is received, the TRIG SGL command is encountered which suspends subprogram execution until the 100 readings are taken. After the readings are taken, the message TEST FINISHED is displayed.
SWEEP sample to the next. For sub-sampling, the valid range of this parameter is 10E-9 to 6000 seconds with 10ns increments; for all other measurement functions the range is ( l/maximum reading rate) to 6000 seconds in 100ns increments. Power-on effective_interval = 100E-9 Default effective_interval = 20µs #_samples Specifies the number of samples to be taken. The valid range for this parameter is 1 to 1.67E+7.
SWEEP 30 Num_samples=lOOO !DESIGNATE NUMBER OF SAMPLES 40 Eff_int=2.
T T T is an abbreviation for the TRIG command. Syntax T [event] Refer to the TRlG command for more information. TARM Trigger arm. Defines the event that enables (arms) the trigger event (TRIG command). You can also use this command to perform multiple measurement cycles. Syntax TARM [event][,number_arms] event The event parameter choices are: event Parameter Numeric Query Equiv. Description AUTO 1 Always armed EXT 2 Arms following a low-going TTL transition on the Ext Trig connector.
TARM Default number_arms = 1 (multiple arming disabled) Remarks • For all measurement functions except sub-sampling (see Chapter 5), the trigger arm event operates along with the trigger event (TRIG command) and the sample event (NRDGS or SWEEP command). To make a measurement, the trigger arm event must occur first, followed by the trigger event, and finally the sample event. • The trigger arm event does not necessarily trigger the multimeter.
TBUFF all measurement cycles are complete. If you want to regain control of the bus immediately, suppress the cr lf by replacing line 60 with: 60 OUTPUT 722 USING "#,K"TARM SGL, 5;" In the above line, the # image specifier suppresses the cr lf. The K image specifier suppresses trailing or leading spaces and outputs the command in free-field format. Notice the semicolon following the TARM SGL.5. This indicates the end of the command to the multimeter and must be present when you suppress cr lf.
TEMP? TEMP? Temperature Query. Returns the multimeter's internal temperature in degrees Centigrade. Syntax TEMP? Remarks • Monitoring the multimeter's tempernture is helpful to determine when to perform autocalibration. • Related Commands: ACAL, CAL, CALSTR Example 10 OUTPUT 722; "TEMP?" !READ TEMPERATURE 20 ENTER 722; A !ENTER RESULT 30 PRINT A !PRINT RESULT 40 END TERM On previous multimeters, the TERM command internally connected or disconnected the multimeter's input terminals.
TEST TEST Causes the multimeter to perform a series of internal self-tests. Syntax TEST Remarks • Always disconnect any input signals before you run self-test. If you leave an input signal connected to the multimeter, it may cause a self-test failure. • If a hardware error is detected, the multimeter sets bit 0 in the error register and a more descriptive bit in the auxiliary error register. The display's ERR annunciator illuminates whenever an error register bit is set.
TONE PRESET state, the multimeter uses the NRDGS command. The power-on values for SWEEP can only be used for sub-sampling (since NRDGS does not apply to sub-sampling). • You cannot use the TIMER (or SWEEP) event for AC or AC+DC voltage measurements using the synchronous or random methods (SETACV SYNC or RNDM) or for frequency or period measurements. • Query Command. The TIMER? query command returns the present time interval, in seconds, for the NRDGS timer event.
TRIG The event parameter choices are: event Parameter Numeric Query Equiv. Description AUTO 1 Triggers whenever the multimeter is not busy EXT 2 Triggers on low-going TTL signal on the Ext Trig connector SGL 3 Triggers once (upon receipt of TRIG SGL) then reverts to TRIG HOLD) HOLD 4 Disables readings SYN 5 Triggers when the multimeter's output buffer is empty, memory is off or empty, and the controller requests data.
TRIG multimeter is properly configured. Line 20 suspends measurements by setting the trigger event to HOLD. Lines 30 and 40 configure for 30 DC voltage readings per trigger event. Line 50 generates a single trigger causing the multimeter to make thirty readings. After the readings are complete, the trigger event reverts to HOLD.
Chapter 7 BASIC Language for the 3458A Introduction ......................................................... 261 How It Works ...................................................... 261 BASIC Language Commands ............................. 262 Variables and Arrays ...................................... 262 Math Operations ............................................. 262 Subprogram Definition/Deletion .................... 263 Subprogram Execution Commands ................ 263 Looping and Branching .........
Chapter 7 BASIC Language for the 3458A
Chapter 7 BASIC Language for the 3458A Introduction This chapter describes the BASIC commands supported by the 3458A's internal BASIC language operating system. With this feature, many of your special requirements can be easily satisfied by writing and downloading a simple BASIC subprogram to customize the multimeter's behavior. The following is a list of possible situations where you might find the internal BASIC language to be useful.
• Local variables (all variables are global) • Parameter passing • Any other BASIC commands not listed in this supplement. BASIC Language Commands This section gives you an overview of the BASIC language commands that are supported by the 3458A's internal BASIC language operating system. Refer to the later sections in this chapter for more detailed information and examples on these commands. Variables and Arrays Note All array indexes are 0 to size (option base 0).
DIV, MOD, ABS, SQR, LOG, EXP, LGT, SIN, COS, ATN Binary Operations: AND, OR, EXOR, NOT, BINAND, BINCMP, BINEOR, BINIOR, BIT, ROTATE, SHIFT Subprogram Definition/Deletion SUB sub_name Identifies where the subprogram begins and assigns the name to the subprogram. SUBEND sub_name Identifies where the subprogram ends and also terminates the entry of the subprogram. DELSUB sub_name Deletes the specified subprogram from internal memory.
New Multimeter Commands The following commands are not documented in chapter 6 but are included in this supplement for your convenience. These commands will work with all revisions of the 3458A's instrument firmware (except as noted). ENTER user_variable Transfers a reading from the multimeter's reading memory to a user variable. The multimeter reading is erased after execution. Example: ENTER Dmm OUTPUT user_variable Outputs the present value of a user variable.
3458A BASIC Language Example Program The following example program illustrates the use of the 3458A's internal BASIC language along with the use of new multimeter commands. This program example uses a Series 300 BASIC computer for program development and for downloading the program to the multimeter over the GPIB interface. The multimeter's bus address is 22 and the computer's GPIB interface address is set to 700.
500 510 520 530 540 Sample Results From Program Execution: ENTER @Dvm; Mean ! Read M into computer T2=TIMEDATE ! Store end time PRINT"MEAN";Mean;"TRANSFER AND CALCULATION SPEED";T2-T1-(T1 -T0) PRINT END MEAN 54.73391112 TRANSFER AND CALCULATION SPEED .399963378906 Variables and Arrays The 3458A employs two forms of numeric variables: simple variables (also called "scalars") and subscripted arrays. Variable usage in the 3458A is very similar to variable usage in an enhanced BASIC language.
in an assignment statement with the LET command. For example, the following statements automatically declare the variable names specified. OUTPUT 722; "LET A=SIN(.223)" OUTPUT 722; "LET B=3.14159" Some 3458A commands expect a specific variable type when defining variables for parameters. For example, the TIME command expects a real number. Similarly, commands which return numeric results will return specific number types. The LINE? command returns an integer number. Measurements returned are real numbers.
OUTPUT 722; "LET TIME_INT =40*3E-3" Variables can replace numeric parameters in any 3458A command that uses numeric parameters. Two examples uses are (1) numeric data storage and (2) numeric calculations. The following sections discuss these two uses. Variables for Data Storage At power-on, numeric output data generated by the 3458A is placed into the GPIB output buffer where it can be sent to the system controller.
the maximum array size is determined by available 3458A memory (approximately 10 kbytes if no stored states or subprograms are stored). A non-integer subscript is rounded to the nearest integer. Arrays may be resized by re-declaring them. This initializes each element in the array to a value of zero. You cannot, however, redefine the type of array (real or integer) without scratching memory first (refer to the SCRATCH command in chapter 6).
general math functions, trigonometric functions, and binary functions are available. The 3458A also has a simple calculator mode. Math Operators In addition to the standard math operators (+ – * / ^), two additional arithmetic operators exist in the 3458A. These operators are DIV (integer division) and MOD (modulo). Unary minus operations should be written as: A = 0-B The DIV command returns the integer portion of a division.
Function/Argument Trigonometric Functions e : Natural antilogarithm. Raises e to the power of the argument. LGT(X) Log10: Common logarithm of a positive argument to the base 10. x Three trigonometric functions are provided in the 3458A. The trigonometric functions are shown in the following table. Function/Argument SIN(X) Logical Functions Meaning EXP(X) Meaning (X in radians) Sine of argument. COS(X) Cosine of argument. ATN(X) Arctangent of argument.
Function/Argument Meaning ROTATE(X,displacement) Returns an integer obtained by rotating the argument a specified number of positions with bit wraparound.* SHIFT(X,displacement) Returns an integer obtained by rotating the argument a specified number of positions without bit wraparound.* * If the displacement is positive, rotating or shifting is toward the least significant bit. If the displacement is negative, rotating or shifting is toward the most significant bit.
20 OUTPUT 722; "LET A=25.3765477" 30 OUTPUT 722; "IF SIN(A)^2 + COS(A)^2 = 1 THEN" 40 OUTPUT 722; " DISP 'EQUAL'" 50 OUTPUT 722; "ELSE" 60 OUTPUT 722; " DISP'NOT EQUAL'" 70 OUTPUT 722; " ENDIF" 80 OUTPUT 722; "SUBEND" 90 ! 100 OUTPUT 722; "CALL TESTER" 110 END You may find that the equality test fails due to rounding errors or other errors caused by the inherent limitations of finite machines. A repeating decimal or irrational number cannot be represented exactly in any finite machine like the 3458A.
depends on the individual sizes of the subprograms. A typical subprogram containing 10 commands (including the SUB and SUBEND commands) might average about 600 bytes. Refer to chapter 3 for more information on memory usage. Can I Nest Subprograms? Yes! Nesting subprograms is the ability to have one subprogram call (execute) another subprogram. You can nest up to 10 subprograms.
The subprogram will not be stored if a subprogram nesting error exists when the SUBEND command is executed (e.g., if one of the called subprograms does not exist in 3458A memory). If you create or download a subprogram using a subprogram name which already exists in 3458A memory, the new subprogram overwrites the previous subprogram. Subprogram Command Types The 3458A's subprogram-related commands are used only within subprograms. Subprogram definition and deletion commands deal with the storage.
itself from the catalog listing of subprograms (CAT command). SCRATCH CAT The SCRATCH command deletes (scratches) all 3458A subprograms, variables, and arrays from internal memory. It also deletes all name definitions from the catalog listing (CAT command). If SCRATCH is executed when a subprogram is running, an error is generated but the subprogram is not purged from memory.
Execution Commands Subprogram execution commands control the execution of a subprogram. The syntax statements for the subprogram execution commands are shown below. CALL sub_name PAUSE CONT Subprogram CALL The CALL command executes the named subprogram and waits for completion before executing other commands This means that no subsequent commands are accepted (either from the GPIB interface or the front-panel keyboard) until the subprogram finishes.
in the subprogram. The RETURN command returns control to the caller without executing the SUBEND command. For example, 10 OUTPUT 722; "SUB DMM_CONF" 20 OUTPUT 722; "DCV 8, 0.00125" 30 OUTPUT 722; "TRIG SGL" 40 OUTPUT 722; "ENTER A' 60 OUTPUT 722; "IF A<5.
command is shown below. FOR counter = initial_value TO final_value [STEP step_size] program segment NEXT counter The counter parameter is a variable name which acts as the loop counter. The initial_value parameter and final_value parameter may be numbers, numeric variables, or numeric expressions. The optional step_size parameter may be a number or numeric expression which specifies the amount the loop counter is incremented for each pass through the loop.
130 END IF...THEN Branching The IF...THEN command provides conditional branching within 3458A subprograms. The syntax statements for the IF...THEN command is shown below. IF expression THEN program segment [ ELSE ] [ program segment ] ENDIF The ENDIF statement must follow the IF...THEN statement somewhere in the subprogram. ELSE is an optional statement, but if used must appear before the ENDIF statement. All commands after the IF...
Appendix A Specifications Introduction ......................................................... 283 DC Voltage .......................................................... 284 Resistance ............................................................ 285 DC Current .......................................................... 287 AC Voltage .......................................................... 288 AC Current .......................................................... 293 Frequency/ Period ...................
Appendix A Specifications
Appendix A Introduction The 3458A accuracy is specified as a part per million (ppm) of the reading plus a ppm of range for dcV, Ohms, and dcl. In acV and acl, the specification is percent of reading plus percent of range. Range means the name of the scale, e.g. 1 V, 10 V, etc.; range does not mean the full scale reading, e.g. 1.2 V, 12 V, etc. These accuracies are valid for a specific time from the last calibration.
1 / DC Voltage 1. Additional error from Tcal or last ACAL ± 1 º C. DC Voltage 2. Additional error from Tcal ±5º C 3. Specifications are for PRESET, NPLC 100. 4. For fixed range (> 4 min.), MATH NULL and Tcal ±1ºC. 5. Specifications for 90 day, 1 year and 2 year are within 24 hours and ±1º C of last ACAL; Tcal ±5ºC, MATH NULL and fixed range. Range Full Scale Maximum Resolution 100 mV 1V 10 V 100 V 1000 V 120.00000 1.20000000 12.0000000 120.000000 1050.
Reading Rate (Auto-Zero Off) Selected Reading Rates 1 Readings / Sec A-Zero NPLC Aperture Digits Bits A-Zero On Off 0.0001 0.0006 0.01 0.1 1 10 100 1000 1.4 µs 10 µs 167 µs2 1.67 ms2 16.6 ms2 0.166 s2 4.5 5.5 6.5 6.5 7.5 8.5 8.5 8.5 16 18 21 21 25 28 28 28 100,000 3 50,000 5,300 592 60 6 36/min 3.6/min 4,130 3,150 930 245 29.4 3 18/min 1.8/min 1. For PRESET; DELAY 0; DlSP OFF; OFORMAT DINT; ARANGE OFF. 2. Aperture is selected independent of line frequency (LFREQ).
2 Accuracy1 (ppm of Reading + ppm of Range) Range 10 W 100 W 1 kW 10 kW 100 kW 1 MW 10 MW 100 MW 1 GW 24 Hour 2 5+3 3+3 2+0.2 2+0.2 2+0.2 10+1 50+5 500+10 0.5%+10 90 Day3 15+5 10+5 8+0.5 8+0.5 8+0.5 12+2 50+10 500+10 0.5%+10 1 Year3 15+5 12+5 10+0.5 10+0.5 10+0.5 15+2 50+10 500+10 0.5%+10 2 Year3 20+10 20+10 15+1 15+1 15+1 20+4 75+10 0.1%+10 1%+10 1. Specifications are for PRESET; NPLC 100; OCOMP ON; OHMF. 2. Tcal ± 1°C. 3.
3 / DC Current DC Current (DCI Function) Range 100 nA 1 µA 10 µA 100 µA 1 mA 10 mA 100 mA 1A Full Scale 120.000 1.200000 12.000000 120.00000 1.2000000 12.000000 120.00000 1.0500000 Maximum Shunt Burden Resolution Resistance Voltage 1 pA 1 pA 1 pA 10 pA 100 pA 1 nA 10 nA 100 nA 545.2 kW 45.2 kW 5.2 kW 730 W 100 W 10 W 1W 0.1 W 0.055 V 0.045 V 0.055 V 0.075 V 0.100 V 0.100 V 0.250 V <1.
4 / AC Voltage General Information The 3458A supports three techniques for measuring true rms AC voltage, each offering unique capabilities. The desired measurement technique is selected through the SETACV command. The ACV functions will then apply the chosen method for subsequent measurements. The following section provides a brief description of the three operation modes along with a summary table helpful in choosing the technique best suited to your specific measurement need.
AC Accuracy (continued): 24 Hour to 2 Year (% of Reading + % of Range) Range 10 mV 100 mV – 10 V 100 V 1000 V ACBAND >2 MHz 45 Hz to 100 kHz 100 kHz to 1 MHz 1 MHz to 4 MHz 4 MHz to 8 MHz 8 MHz to 10 MHz 0.09 + 0.06 1.2 + 0.05 7 + 0.07 20 + 0.08 0.09 + 0.06 2.0 + 0.05 4 + 0.07 4 + 0.08 15 + 0.1 0.12 + 0.002 0.3 + 0.01 Transfer Accuracy Range % of Reading 100 mV – 100 V (0.002 + Resolution in %)1 Conditions • Following 4 Hour warm-up • Within 10 min and ±0.
Maximum Input High Frequency Temperature Coefficient For outside Tcal ±5°C add the following error. (% of Reading)/°C HI to LO LO to Guard Guard to Earth Volt – Hz Product Frequency Range 2 – 4 MHz 4 – 10 MHz 10 mV – 1 V 0.02 0.08 10 V – 1000 V 0.08 0.08 Rated Input ±1000 V pk ±200 V pk ±500 V pk 1x108 Non-Destructive ±1200 V pk ±350 V pk ±1000 V pk Analog Mode (ACV Function, SETACV ANA) Range Maximum Full Scale Resolution 10 mV 100 mV 1V 10 V 100 V 1000 V 12.00000 120.0000 1.200000 12.00000 120.
Reading Rates 1 1. Sec / Reading ACBAND Low ³10 Hz ³1 kHz ³10 kHz NPLC 10 1 0.1 ACV 1.2 1 1 For DELAY–1: ARANGE OFF For DELAY 0; NPLC .1 , unspecified reading rates of greater than 500/Sec are possible. ACDCV 1 0.1 0.02 Settling Characteristics For first reading or range change error using default delays, add .01% of input step additional error. The following data applies for DELAY 0.
AC + DCV Accuracy (ACDCV Function) For ACDCV Accuracy apply the following additional error to the ACV accuracy. (% of Range). DC £10% of AC Voltage ACBAND ACBAND Temperature Range £ 2 MHz >2 MHz Coefficient 1 10 mV 0.09 0.09 0.03 100 mV–1 kV 0.008 0.09 0.0025 DC >10% of AC Voltage ACBAND ACBAND Temperature £ 2 MHz >2 MHz Coefficient1 0.7 0.7 0.18 0.07 0.7 0.025 1. Additional Errors Apply the following additional errors as appropriate to your particular measurement setup.
5 / AC Current AC Current (ACI and ACDCI Functions) Range 100 µA 1 mA 10 mA 100 mA 1A Maximum Resolution 100 pA 1 nA 10 nA 100 nA 1 µA Full Scale 120.0000 1.200000 12.00000 120.0000 1.050000 Shunt Resistance 730 W 100 W 10 W 1W 0.1 W Burden Voltage 0.1 V 0.1 V 0.1 V 0.25 V < 1.5 V Temperature Coefficient 1 (% of Reading + % of Range) / °C 0.002+0 0.002+0 0.002+0 0.002+0 0.002+0 1. Additional error beyond ±1°C, but within ±5°C of last ACAL. 2.
Settling Characteristics For first reading or range change error using default delays, add .01% of input step additional error for the 100 µA to 100 mA ranges. For the 1 A range add .05% of input step additional error. The following data applies for DELAY 0. Function ACBAND Low ³10 Hz ACI ACDCI DC Component DC < 10% AC Settling Time 0.5 sec to 0.01% DC > 10% AC 0.9 sec to 0.01% 0.5 sec to 0.01% 0.08 sec to 0.01% 0.015 sec to 0.
7 / Digitizing Specifications General Information The 3458A supports three independent methods for signal digitizing. Each method is discussed below to aid in selecting the appropriate setup best suited to your specific application. DCV Standard DCV function. This mode of digitizing allows signal acquisition at rates from 0.2 readings / sec at 28 bits resolution to 100k readings / sec at 16 bits. Arbitrary sample apertures from 500 ns to 1 sec are selectable with 100 ns resolution.
Dynamic Performance 100 mV, 1 V, 10 V Ranges; Aperture = 6 µs Test DFT-harmonics DFT-spurious Differential non-linearity Signal to Noise Ratio Input (2 x full scale pk-pk) 1 kHz 1 kHz dc 1 kHz Result < –96 dB < –100 dB < 0.
8 / System Specifications Function-Range-Measurement The time required to program via GPIB a new measurement configuration, trigger a reading, and return the result to a controller with the following instrument setup: PRESET FAST; DELAY 0; AZERO ON; OFORMAT SINT; INBUF ON; NPLC 0.
9 / Ratio Type of Ratio 1 DCV / DCV ACV / DCV ACDCV / DCV 1. Ratio = (Input) / (Reference) Reference: (HI Sense to LO) – (LO Sense to LO) Reference Signal Range: ±12 V DC (autorange only) Accuracy ± (Input error + Reference Error) Input error = 1 × Total Error for input signal measurement function (DCV, ACV, ACDCV) Reference error = 1.
11 / General Specifications Operating Environment Temperature Range: 0°C to 55°C Operating Location: Indoor Use Only Operating Altitude: Up to 2,000 Meters Pollution Rating: IEC 664 Degree 2 Warranty Period One year Operating Humidity Range up to 95% RH at 40°C Input Limits Input HI to LO: 300 Vac Max (CAT II) Physical Characteristics 88.9 mm H x 425.5 mm W x 502.9 mm D Net Weight: 12 kg (26.5 lbs) Shipping Weight 14.8 kg (32.5 lbs) IEEE-488 Interface Complies with the following: IEEE-488.
Appendix A Specifications
Appendix B GPIB Commands Introduction ......................................................... 303 ABORT 7 (IFC) .............................................. 304 CLEAR (DCL or SDC) .................................. 304 LOCAL (GTL) ............................................... 304 LOCAL LOCKOUT (LLO) ........................... 305 REMOTE ........................................................ 305 SPOLL (Serial Poll) ....................................... 306 TRIGGER (GET) .........................
Appendix B GPIB Commands
Introduction Appendix B GPIB Commands Introduction The BASIC language GPIB commands in this appendix are specifically for HP Series 200/300 computers. Any IEEE-488 controller can send these messages; however, the syntax may be different from that shown here. The IEEE-488 terminology is shown in parentheses following each command title. All syntax statements and examples assume an interface select code of 7 and the device address of 22. Table B-l shows the multimeter's GPIB capabilities.
ABORT 7 (IFC) ABORT 7 (IFC) Clears the multimeter's interface circuitry. Syntax ABORT 7 Example ABORT 7 !CLEARS THE MULTIMETER'S INTERFACE CIRCUITRY CLEAR (DCL or SDC) Clears the multimeter, preparing it to receive a command. The CLEAR command does the following: • Clears the output buffer. • Clears the input buffer. • Aborts subprogram execution. • Clears the status register (bits 4, 5, and 6 are not cleared if the condition(s) that set the bit(s) still exist).
LOCAL LOCKOUT (LLO) Examples LOCAL 7 !SETS GPIB REN LINE FALSE (ALL DEVICES GO TO LOCAL). (YOU MUST NOW EXECUTE REMOTE 7 TO RETURN TO REMOTE MODE). LOCAL 722 !ISSUES GPIB GTL TO DEVICE AT ADDRESS 22. (AFTERWARDS, EXECUTING ANY MULTIMETER COMMAND OR REMOTE 722 RETURNS THE MULTIMETER TO REMOTE MODE. LOCAL LOCKOUT (LLO) Disables the multimeter's LOCAL key. Syntax LOCAL LOCKOUT 7 Remarks • If the multimeter is in the local state when you send LOCAL LOCKOUT, it remains in local.
SPOLL (Serial Poll) Examples REMOTE 7 !SETS GPIB REN LINE TRUE The above line does not, by itself, place the multimeter in the remote state. The multimeter will only go into the remote state when it receives its listen address (e.g., sending OUTPUT 722;"BEEP"). REMOTE 722 !SETS REN LINE TRUE AND ADDRESSES DEVICE 22 The above line places the multimeter in the remote state.
TRIGGER (GET) TRIGGER (GET) If triggering is armed (see TARM command), the TRIGGER command (Group Execute Trigger) triggers the multimeter once, and then holds triggering. Syntax TRIGGER 7 TRIGGER 722 Remarks • The TRIGGER command generates a single trigger just as if the TRIG SGL command was executed. It will not, however, trigger the multimeter if triggering is not armed (TARM command).
TRIGGER (GET) 308 Appendix B GPIB Commands
Appendix C Procedure to Lock Out Front/ Rear Terminals and Guard Terminal Switches Introduction ......................................................... 311 Tools Required .................................................... 311 Procedure ............................................................. 311 Covers Removal Procedure ............................ 312 Guard Pushrod Removal Procedure ............... 314 Front/Rear Pushrod Removal Procedure ........ 314 Switch Cap Installation Procedure ............
Appendix C Procedure to Lock Out Front/Rear Terminals and Guard Terminal Switches
Appendix C Procedure to Lock Out Front/Rear Terminals and Guard Terminal Switches Introduction Either or both the Front/Rear Terminals and Guard Terminal switches can be locked out to prevent changing their settings. To do this, first remove all covers from the 3458. Then, remove the pushrods from the Front/Rear and Guard switches. Next, place switch covers over the holes where the pushrods previously protruded through. The switch covers are in the Front/Rear Terminal and Guard Switch Lockout kit.
Covers Removal Procedure Do the following: 1. Remove any connections to the 3458. 2. Remove ac power from the 3458. 3. Refer to Figure 35. Turn the instrument so its right side faces you (as seen from the front). Figure 35. 3458 Right side 4. Use the #l pozidriv to remove the right side handle strap screws. Then remove the strap. 5. Refer to Figure 36. Turn the instrument so its left side faces you. 6. Use the #1 pozidriv to remove the left side handle strap screws. Then remove the strap. 7.
Figure 36. 3458 Left side Figure 37.
Figure 38. 3458 Rear view Guard Pushrod Removal Procedure If you DO NOT wish to lockout the Guard switch, continue with the next paragraph. 1. Refer to Figure 39. Use the #TX 10 Torx driver to remove the bottom shield screw. Then remove the shield. Pull the shield toward the rear of the instrument until the shield retainers line up with the slots in the shield. Lift the shield off. 2. Refer to Figure 40, Locate the pushrod for the Guard switch. Pull the pushrod off.
Figure 39. 3458 Inside bottom view Figure 40.
Figure 41. 3458 Inside top view 3. Refer to Figure 42. Locate the pushrod for the Front/Rear Terminal switch. Pull the pushrod off. You may need to pry the pushrod loose with a small flat blade screwdriver, Set the switch in the position it is to be used. 4. Refer to Figure 41. Replace the top shield. Line up the slots on the shield with the shield retainers. Then push the shield toward the front of the instrument until the shield screw hole lines up with the hole in the chassis.
Figure 42. Front/rear terminal switch and pushrod location Figure 43.
Covers Installation Procedure Do the following: 1. Turn the 3458 over so its top sits on your workbench. 2. Install the bottom cover by placing it into the slots of the instrument side castings, Then push the cover toward the front of the instrument into the front panel bezel. 3. Turn the 3458 over so the bottom sits on your workbench. 4. Install the top cover by placing it into the slots of the instrument side castings. Then push the cover toward the front of the instrument into the front panel bezel. 5.
Appendix D Optimizing Throughout and Reading Rate Introducing the 3458A ......................................... 321 Application Oriented Command Language .... 321 Intrinsically Slow Measurements ................... 321 Maximizing the Testing Speed ............................ 322 Program Memory ........................................... 322 State Storage ................................................... 322 Reading Analysis ............................................ 322 Task Grouping and Sequence ...
Appendix D Optimizing Throughout and Reading Rate
Appendix D Optimizing Throughout and Reading Rate (From Product Note 3458A-1) In the past decade and a half, microcomputers have greatly improved both their internal speed and their speed of communication with other equipment. The actual clock rates of microcomputers used in instrumentation has gone from under 1 MHz to over 12 MHz and the data bus has gone from 8 bits to 16 bits.
the speed of testing. For example, in many systems accuracy can be traded for speed; or flexibility in timing the measurement can lead to real increases in the rate of rms AC measurements with good accuracy. The set of trade-offs one may make with the 3458A Multimeter is covered in detail in this Product Note. Maximizing the Testing Speed Program Memory The speed of the testing process can also be maximized by tailoring the communication path between the 3458A and the computer.
throughput and still provides 70% of the overhead programming like Statistical Quality Control (SQC) and inventory management. System Uptime Longer system up-time also means higher test system throughput. The 3458A's Multimeter performs a complete self-calibration of all functions, including AC, using high-stability internal standards. This self- or auto-calibration eliminates measurement errors due to time drift or temperature changes in your rack or on your bench for superior accuracy.
track-and-hold path can accept signals up to 12 MHz. The track-and-hold path is limited to 16 bits of resolution unless repeated measurements are made. The DCV path can present up to 8 1/2 digits (27 bits) resolution. Optimizing Through the DCV Path The classic trade-offs one can make with the 3458A are measurement speed versus measurement resolution.
Figure 44. Shows the dependency of accuracy, reading rate, resolution, and noise on aperture or NPLC selected. Table 30: Integration time and query response. Command Integration Time (APER) Query Response (NPLC?) 50 Hz 60 Hz 50 Hz 60 Hz 500 ns 500 ns 25 E-6 29.99994 E-6 NPLC.5 10ms 8.333 ms 500 E-3 499.99700 E-3 NPLC 1 20 ms 16.6667 ms 1 1 200 ms 166.667 ms 10 10 200 ms 166.
and DCV,20;RES.001 (omitting the resolution parameter of the DCV command and using the RES command) both set the 3458A to DCV, the 100 V range, the integration period to 8 µs, and set the resolution to .00l% of 20 V. The reading rate can be doubled simply by turning the auto zero operation off. Auto zero on (AZERO,ON) is the default condition of the 3458A.
Figure 45. Settling time characteristic for resistance measurements assuming <200pF shunt capacitance in the circuit tested. For small values of resistance, there is no real advantage to setting the delay to less than the default values. Resistance above 100 kW require longer settling times to reach final values: hence settling delay times for these values may save measurement time at the expense of measurement accuracy. Another feature of the 3458A is OffsetCompensated Ohms.
Optimizing Through the Track-and-Hold Path (Direct Sampling and Subsampling) As stated earlier, the standard DCV path directs the signal to the A to D Converter. This path exhibits 150 kHz bandwidth and selectable resolution from 4 1/2 to 8 1/2 digits. The track-and- hold path exhibits 12 MHz bandwidth and 4 1/2 digits of resolution. This path uses a 16 bit track-and-hold circuit between the input and the A to D to take a "snapshot" of the input.
the resolution of the measurement is dependent upon the number of samples, this mode of operation is the least accurate and the slowest of the ACV functions for high resolution. Aliasing (discussed in detail in the Digitizing Product Note 3458A-2) is avoided by a random selection of sampling intervals from 20 to 40 µs in 10 ns increments. Comparison of ACV Modes With all three ACV modes of operation, the user has the option of selecting accuracy versus speed if the input frequency allows.
Frequency and Period The track-and-hold path is also the route the signal must take for frequency and its reciprocal, period. The 3458A offers frequency response from 10 Hz to 10 MHz to 7½ digits with a maximum gate time of 1 second. One can trade speed for accuracy and resolution by selection of shorter gate times of the internal counter. Table 32 shows the trade-off of resolution for each of the gate times. Table 32: Shows resolution trade off for each of the gate times.
storage. The transfer rate into and out of the Reading Memory and the GPIB transfer rate using direct memory access with an HP 9000 Series 200/300 computer is 100,000 readings per second. The advantage of the memory is that one may access the data when it is convenient for the controller and not have to tie the system up waiting for the measurement to finish (a long integration period, a long settling time, or an average of multiple readings can cause even the fastest dmm to hold up the system).
Measurement List The most efficient method of using the 3458A within a system is to establish a measurement list in Program Memory that corresponds with a channel list in the signal switching instrument. The 358A's External Output is connected to the Channel Advance input of the switching instrument and the Channel Closed output of the switching instrument is connected to the External Trigger input of the 3458A.
A Benchmark The benchmark used to show the affect of the various functions of the 3458A Multimeter will start with the most convenient, but least rapid, procedure of having the computer ask the dmm to change to a particular function, make a measurement, and transfer the measurement to the computer. The benchmark will assume that all of the measurements will be made through a FET scanner of infinitely fast switching speed and of infinite dynamic range.
1 DCV <1 V ±.001% 1 ACV <10 V ±.1% 1 DCV <10 V ±1% 3 DCV <10 V ±.01% Benchmark Results Default Conditions: (Subprogram Default) time = 20.63 s. 560 570 580 590 600 610 620 630 640 ... SUB Default(REAL Dnld_time.
1180 1190 1200 1210 1220 1230 1240 1250 DIM A(37) Exe_time=TIMEDATE OUTPUT 722;"PRESET" OUTPUT 722;"OHM,lE4;NPLC 0" FOR I=1 TO 15 ENTER 722;A(I) NEXT I OUTPUT 722;"OHM,1E5" ...
... 1940 1950 1960 1970 1980 1990 2000 2010 2020 OUTPUT 722;"DCV,10;NPLC 0;DELAY 0;NRDGS 3;TRIG SGL Exe_time=TIMEDATE-Exe_time Dnld_time=0 Tns_time=TIMEDATE FOR I=1 TO 37 ENTER 722;A(I) NEXT I Tns_time=TlMEDATE-Tns_time SUBEND A marked change is effected in the structure of the program. Now the readings are stored in Reading Memory as the measurements are made. At the end of the measurement sequence, the readings are transferred from Reading Memory to the computer using a FOR NEXT loop.
be: OUTPUT 722 USING "#,K"; "CALL 1" By using the image "#,K", the End-Of-Line (EOL) terminators are suppressed. When the 3458A receives the command without a terminator, it releases the computer so that the computer can continue the program while the 3458A continues with the operations it was requested to do. Note that the execution time for the benchmark is markedly less than just using Reading Memory. Display Off: (Subprogram Display) test execution time = .500 s program memory download time = .
Still Faster A considerable increase in throughput can be had if you use TRANSFER statements instead of OUTPUT and ENTER statements. Further, the juxtaposition of some commands improve the measurement speed. Notably, the sequence for DELAY and ACBAND when working with ACV can make a large difference in execution speed. The proper sequence is: DELAY <#>;ACBAND <#,#>;ACV . If you want to change the default settling times when you change a function, always change the DELAY command first.
350 360 370 380 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 320 330 340 350 360 370 380 390 400 410 420 430 PRINT "EXECUTION TIME =";Exe_time PRINT "TRANSFER TIME = ";Tns_time PRINT "TOTAL TIME = "; Dnld_time+Exe_time+Tns_time END ! Bench Mark Test ! COM Dnld_trme.Exe_time,Tns_time ! CALL Default(Dnld_time,Exe_time,Tns_time) PRINT USING "36A.DD.DDD";"The execution time for default is ";Exe_time PRINT ! CALL Fixed(Dnld_time.
440 PRINT USING "44A,DD,DDD";"The transfer time using FOR NEXT is ";Tns_time 450 PRINT USING "44A,DD.DDD";"The total time for AZERO off is"; Exe_time+Dnld_time+ Tns_time 460 PRINT 470 ! 480 CALL Defeat(Dnld_time,Exe_time,Tns_time) 490 PRINT USING "44A,DD.DDD";"The execution time for program memory is ";Exe_time 500 PRINT USING "44A,DD,DDD";"The download time for transfering the SUB is";Dnld_time 510 PRINT USING "44A,DD,DDD";"The transfer time using FOR NEXT is ";Tns_time 520 PRINT USING "44A,DD.
1030 1040 1050 1060 1070 1080 1090 1100 1110 1120 1130 1140 1150 1160 1170 1180 1190 1200 1210 1220 1230 1240 1250 1260 1270 1280 1290 1300 1310 1320 1330 1340 1350 1360 1370 1380 1390 1400 1410 1420 1430 1440 1450 1460 1470 1480 1490 1500 1510 1520 1530 1540 1550 1560 1570 1580 1590 1600 1610 1620 1630 1640 1650 1660 1670 OUTPUT 722;"DCV, 10" FOR I=28 TO 33 ENTER 722;A(l) NEXT I OUTPUT 722;"ACV,10;ACBAND 5000" ENTER 722;A(34) OUTPUT 722;"DCV,10" FOR I=35 TO 37 ENTER 722;A(I) NEXT I Exe_time=TIMEDATE-Exe_t
1680 1690 1700 1710 1720 1730 1740 1750 1760 1770 1780 1790 1800 1810 1820 1830 1840 1850 1860 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 2100 2110 2120 2130 2140 2150 2160 2170 2180 2190 2200 2210 2220 2230 2240 2250 2260 2270 2280 2290 2300 2310 2320 342 ENTER 722;A(27) OUTPUT 722;"DCV,10;NPLC 0;DELAY 0" FOR I=28 TO 33 ENTER 722;A(I) NEXT I OUTPUT 722;"ACV,10;ACBAND 5000;APER 20E-6; DELAY .
2330 2340 2350 2360 2370 2380 2390 2400 2410 2420 2430 2440 2450 2460 2470 2480 2490 2500 2510 2520 2530 2540 2550 2560 2570 2580 2590 2600 2610 2620 2630 2640 2650 2660 2670 2680 2690 2700 2710 2720 2730 2740 2750 2760 2770 2780 2790 2800 2810 2820 2830 2840 2850 2860 2870 2880 2890 2900 10 20 30 40 50 60 OUTPUT 722;"ACV 10;ACBAND 25000;DELAY .01;TRIG SGL" OUTPUT 722:"DCV,10;NPLC 0;DELAY 0;NRDGS 6;TRIG SGL" OUTPUT 722;"ACV,10;ACBAND 5000;APER 20E-6;DELAY .
70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 320 330 340 350 360 370 380 390 400 410 420 430 440 450 460 461 462 463 470 480 490 500 510 520 530 540 550 560 570 580 590 600 610 620 630 640 650 344 SUB Test_58(Time58) DIM A(20),B(90),C(30),D(30),J$[80] !SET UP SCANNER ASSIGN @Scan TO 709 ASSIGN @Dmm TO 722 CLEAR @Dmm OUTPUT @Dmm;"RESET" !Sets the dmm to power-up state OUTPUT @Dmm;"TRIG HOLD" ! Stops triggering ! ! -------- ScannerSetup -------! OUTPUT @Sc
660 670 680 690 700 710 720 730 740 750 760 770 780 790 800 810 820 830 840 850 860 870 880 890 900 910 920 930 940 950 OUTPUT @Dmm;"ACV 10"!Sets the dmm to 10 volts maximum input in acV OUTPUT @Dmm;"TARM SGL"! (3 OUTPUT @Dmm;"TARM SGL"! (4) OUTPUT @Dmm:"DCV 10” OUTPUT @Dmm;"TARM SGL"! (4) OUTPUT @Dmm;"TARM SGL"! (5) OUTPUT @Dmm;"ACV 10" OUTPUT @Dmm;"TARM SGL"! (5) OUTPUT @Dmm;"TARM SGL"! (6) OUTPUT @Dmm;"DCV 10" OUTPUT @Dmm;"TARM SGL"! (6) OUTPUT @Dmm;"TARM SGL"! (7) OUTPUT @Dmm;"OHM 3E3"!Sets the dmm to
Appendix D Optimizing Throughout and Reading Rate
Appendix E High Resolution Digitizing With the 3458A Introduction ......................................................... 349 Speed with Resolution ......................................... 349 Digitizing Analog Signals .............................. 350 Avoiding Aliasing .......................................... 350 Choice of Two Measurement Paths ..................... 351 Using the DCV Path for Direct Sampling ...... 351 Using the Track-and-Hold Path for Direct or Sequential Sampling ..................
Appendix E High Resolution Digitizing With the 3458A
Appendix E High Resolution Digitizing With the 3458A (From Product Note 3458A-2) Introduction In your system or stand-alone with your computer, the 3458A can digitize wave forms with low distortion and very high resolution. The 3458A has the measurement speed and precise timing necessary for direct sampling of signals with frequency components up to 50 kHz or, with repetitive signals, subsampling up to 12 MHz with 16 bits of resolution and more. In this product note you will learn how to: 1.
measurement-to-measurement jitter. Through the track-and-hold path, the 3458A can digitize repetitive signals up to 12 MHz at 50 kSamples/s with 16 bits resolution by using sequential sampling (subsampling). Digitizing Analog Signals Most digital signal processing systems may be represented as illustrated in Figure 50.
Figure 51. Direct sampling acquires the wave form in one pass of the input. Sequential sampling requires a repetitive signal where the period is reconstructed in several passes. The numbers shown represent samples acquired in one period of the input. Choice of Two Measurement Paths The 3458A provides two different input measurement paths: the standard DCV path and the track-and-hold path (see Figure 52). The track-and hold path is used for subsampling and direct sampling.
Figure 52. The 3458A Multimeter provides two different digitizing paths, the standard DCV path and a track-and-hold path. Using the Track-and-Hold Path for Direct or Sequential Sampling The track-and-hold path is the solution to capturing the amplitude of narrow pulses. This path has a bandwidth of 12 MHz and a fixed aperture of 2 ns.
digitizing, two additional commands are used for direct sampling and subsampling: SWEEP which is related to NRDGS, and SSRC which selects the trigger source (level or external) for subsampling. You can choose from a variety of events or conditions that must be satisfied before taking measurements, as shown is Figure 54. The default condition for all three levels of triggering is AUTO; the 3458A will generate its own trigger as fast as the multimeter set-up allows. Figure 54.
TRIG is the next condition to be satisfied. Only after both TARM and TRIG event conditions are satisfied can a burst measurement be made with NRDGS. Refer to Figure 56. NRDGS [# of readings] [,event] lets you specify the number of readings to take, the trigger condition for each reading, and the number of readings saved in memory before or after the trigger event. The SWEEP and SSRC commands are specifically designed to make the task of digitizing easier.
cycle. Two methods suggest themselves for this analysis: (1) sweep the entire frequency spectrum at 100 ns interval or (2) divide the frequency spectrum into bands and sweep these bands at the 1/(2f0) for the band. In the first case, the data acquisition time is minimized, in the second case the need for a fast computer is minimized. Figure 57. Using the 3458A as a phase/gain meter with a swept frequency generator for magnitude only Bode plots.
Figure 58. Here is a typical way to structure your own automatic measurement program using the Library Subprograms (not necessarily a complete list). In addition to time domain analysis like frequency, risetime, pulse width, and overshoot, the Wave Form Analysis Library offers frequency domain analysis with Fast Fourier Transform (FFT) and Inverse Fourier Transform (IFT), with the Hanning filter function.
The subprogram is one of the most powerful elements available in any programming language. Each subprogram has its own context or state as distinct from the main program. This means that every subprogram has its own set of variables and its own line labels. Starter Main Program Every program using the library subprogram requires a main program. Many of the data arrays discussed in this part must be dimensioned in each main program.
Figure 59. Example of results generated using the Wave Form Analysis Library. Errors in Measurements The flexibility of the 3458A helps you avoid or compensate for many of the measurement errors that can occur in the digitizing process. Errors associated with digitizing can be grouped by their amplitude error and time error contributions to the total error in the measurement. For dynamic signals, time errors result in amplitude error.
4. Trigger latency 5. Aperture width 6. Aperture jitter Figure 60. These digitizing error sources should be considered in any measurement. Amplitude Errors The input signal conditioning section of the 3458A has switches (relays), attenuators, and amplifiers associated with conditioning and routing the signal for either the Analog-to-Digital (ADC) or the track-and-hold. Auto zero eliminates input offset errors but the residual error does propagate. This section is the low frequency section of the 3458A.
An inescapable reality in any measurement is the attendant noise with increasing bandwidth. The effects of random measurement noise can be reduced by averaging the measurements. Caused by Johnson noise and other circuit related noise as well as noise on the input signal, the removal of this noise always costs measurement time.
Figure 62. Analog-to-dig ital converters that exhibit non-linearity errors cause spurious responses that averaging will not remove. The 3458A is linear to 16 bits at 100,000 readings/s. The 3458A offers two input paths. The differences are that the direct ADC path (DCV) offers up to 160 kHz bandwidth up to a sampling rate of 100,000 samples per second; the track-and- hold path offers 12 MHz bandwidth at a sampling rate of 50,000 readings per second.
The trigger error is orders of magnitude greater than timebase error and jitter. Two effects cause this. The 3458A has no delay line, so there is a trigger latency, a time delay between the trigger and the commencement of the measurement, that is fixed by the firmware, the clock, and the timing circuits. It is specified to be less than 175 ns for an external trigger. The accuracy of the trigger can also be affected by noise on the trigger signal and time interpolator variation between measurements.
INDEX A A/D converter, configuring the, 58 AC bandwidth, 105 current, 64 measurements, configuring for, 62 voltage, 62 voltage method, specifying the, 64 AC+DC current, 64 voltage, 62 ACAL, 157 ACBAND, 158 Accessories, options and, 16 ACDCI, 159 ACDCI example, fast, 107 ACDCI key, 29 ACDCV, 159 ACDCV example fast analog, 106 fast synchronous, 106 ACDCV key, 29 ACI, 159 ACI example, fast, 107 ACI key, 29 ACV, 159 ACV example fast analog, 106 fast synchronous, 106 ACV key, 29 ADDRESS, 159 Address changing the
Binary coding, two’s complement, 92 Buffering, external trigger, 88 Burst complete, 113 Bus, sending readings across the, 98 C Cable lengths, GPIB, 20 power, 17 Cable, connecting the GPIB, 19 CAL, 164 Calibration, 48 CALL, 164 CALNUM?, 165 CALSTR, 165 Caps line fuse, 21 switch lockout, 311 Changing GPIB address, 43 measurement function, 28 Choices, event, 82 Clear key, 31, 38 Clearing the display, 37 Coding, two’s complement binary, 92 Combinations, event, 88 Command sending a remote, 43 termination, 152 C
Defaulting parameters, 152 DEFEAT, 168 DEFKEY, 169 DELAY, 170 Delay time, 105 Delayed readings, 86 Deleting states, 75 subprograms, 74 DELSUB, 171 Determining the reading rate, 109 Devices, GPIB, maximum number of, 20 DIAGNOST, 171 Digitizing DCV, 134 methods, 129 Digits displayed, 39 DINT example, 100 output format, using, 99 Directly, specifying integration time, 60 Direct-sampling, 137 example, 139 remarks, 138 DISP, 171 Display, 26 clearing the, 37 control, 37 editing, 38 MORE INFO, 39 test, 32 window k
Execution, suspending subprogram, 72 Exponential parameters, 35 External trigger buffering, 88 triggering, 87 EXTOUT, 178 EXTOUT ONCE, 115 EXTOUT signal, 110 F f0 - f9 keys, 40 Factory address setting, 20 Fast ACDCI example, 107 ACI example, 107 analog ACDCV example, 106 analog ACV example, 106 FREQ example, 107 PER example, 107 random ACDCV example, 106 random ACV example, 106 readings, configuring for, 103 synchronous ACV example, 106 Ffast synchronous ACDCV example, 106 FILTER, 124 Filtering, level, 134
INBUF, 185 Increasing the reading rate, 102 Indication, overload, 96, 99 Initial inspection, 15 Input resistance, fixed, 62 terminals, selecting the, 50 Input buffer, 75 Input complete, 114 Input/output statements, 42 Inspection, initial, 15 Installation verification, 21 Installing keyboard overlay, 41 line power fuse, 18 multimeter, 17 Integer double, 92 single, 92 Integration time and resolution, 104 directly, specifying, 60 setting the, 59, 67 Interrupts, 77 ISCALE?, 187 L Language conventions, 152 LEVE
Menu scroll, 36 Methods digitizing, 129 MFORMAT, 198 MMATH, 199 Mode, high-speed, 102 MORE INFO annunciator, 27 display, 39 MORE INFO annunciator, 27 Mounting bench-top, 20 multimeter, 20 rack, 20 MRNG annunciator, 27 MSIZE, 202 Multimeter installing the, 17 mounting the, 20 presetting the, 52 resetting the, 32 Multiple commands, 152 parameters, 35 readings, 83 trigger arming, 84 N NDIG, 203 Nested subprograms, 73 NPLC, 204 NRDGS, 206 Nrdgs/Trig key, 33 NULL, 117 Number of, devices, GPIB, maximum, 20 Numer
fuse, installing the line, 18 fuse, replacing the line, 21 line cycles, specifying, 59 line fuses, 21 requirements line, 17 switch, 25 Power-on self-test, 25 state, 25 PRESET, 216 PRESET FAST command, 103 Presetting the multimeter, 52 PURGE, 218 Q QFORMAT, 218 Queries, standard, 37 Query commands, 37, 153 standard, 153 R R, 220 Rack mount, 20 Random ACDCV example, fast, 106 ACV example, fast, 106 sampling conversion, 64 RANGE, 220 Range, specifying the, 54 Ranging autoranging and manual, 29 manual, 30 RAT
line power fuse, 21 Requirements grounding, 17 line power, 17 RES, 224 RESET, 225 Reset key, 32 Resetting the multimeter, 32 Resistance, 56 fixed input, 62 Resolution integration time and, 104 specifying, 60, 68 when to specify, 61, 69 restricted rights statement, 2 REV?, 227 RMATH, 227 RMEM, 228 RMS conversion, analog, 64 RQS, 229 RSTATE, 230 Running autocal, 49 S safety symbols, 3 Sample event, 82 Samples to memory, 144 to the controller, 144 Sampling rate, 131 remarks, synchronous, 63 Sampling conversio
resolution, 60, 68 Specifying Resolution, when to, 69 SREAL example, 93 output format, 101 SRQ, 27, 235 annunciator, 27 SSAC, 236 SSDC, 236 SSPARM?, 239 SSRC, 239 SSTATE, 243 Standard queries, 37 query commands, 153 Stands, tilt, 20 State memory, using, 74 power-on, 25 State key recall, 33 store, 33 Statement ENTER, 42 OUTPUT, 42 TRANSFER, 42 Statements, Input/output, 42 States deleting, 75 recalling, 74 storing, 74 Statistics, 122 Status register, 75 reading the, 77 STB?, 244 Store State key, 33 Storing st
command, 152 output, 99 TEST, 254 Test key, 30 test, display, 32 tilt stands, 20 Time, delay, 105 Timed readings, 85 TIMER, 254 TONE, 255 Transfer across GPIB, high-speed, 107 from memory, high-speed, 108 TRANSFER statement, 42 TRIG, 255 Trig key, 33 Trigger arming multiple, 84 buffering, external, 88 event, 82 Trigger arm event, 82 Triggering examples, level, 132 external, 87 level, 132 measurements, 81 setup, 105 Two’s complement binary coding, 92 U USER keys, 40 User-defined keys, 40 372 INDEX Using c
Copyright © 1988, 1992, 1994, 2000 Agilent Technologies, Inc. All rights reserved. *03458-90014* Manual Part Number: 03458-90014 Printed in U.S.A.
