www.keithley.com Model 2182/2182A Nanovoltmeter User’s Manual 2182A-900-01 Rev.
WARRANTY Keithley Instruments, Inc. warrants this product to be free from defects in material and workmanship for a period of 3 years from date of shipment. Keithley Instruments, Inc. warrants the following items for 90 days from the date of shipment: probes, cables, rechargeable batteries, diskettes, and documentation. During the warranty period, we will, at our option, either repair or replace any product that proves to be defective.
Model 2182 and 2182A Nanovoltmeter User’s Manual This User’s Manual supports both the Models 2182 and 2182A: References to the Model 2182 apply to both the Models 2182 and 2182A. References to the Model 2182/2182A apply to the Model 2182 with firmaware version A10 or higher, and the Model 2182A with firmware version C01 or higher. References to the Model 2182A applies to the Model 2182A with firmware version C01 or higher. ©2004, Keithley Instruments, Inc. All rights reserved. Cleveland, Ohio, U.S.A.
Manual Print History The print history shown below lists the printing dates of all Revisions and Addenda created for this manual. The Revision Level letter increases alphabetically as the manual undergoes subsequent updates. Addenda, which are released between Revisions, contain important change information that the user should incorporate immediately into the manual. Addenda are numbered sequentially.
Safety Precautions The following safety precautions should be observed before using this product and any associated instrumentation. Although some instruments and accessories would normally be used with non-hazardous voltages, there are situations where hazardous conditions may be present. This product is intended for use by qualified personnel who recognize shock hazards and are familiar with the safety precautions required to avoid possible injury.
bles or jumpers, installing or removing switching cards, or making internal changes, such as installing or removing jumpers. Do not touch any object that could provide a current path to the common side of the circuit under test or power line (earth) ground. Always make measurements with dry hands while standing on a dry, insulated surface capable of withstanding the voltage being measured.
Table of Contents 1 Getting Started General information ................................................................................................ 1-3 Warranty information ....................................................................................... 1-3 Contact information ......................................................................................... 1-3 Safety symbols and terms ................................................................................ 1-3 Inspection ......
Temperature configuration ................................................................................... Measuring voltage and temperature ..................................................................... SCPI programming - voltage and temperature measurements ...................... Low-level considerations ...................................................................................... Thermal EMFs ..............................................................................................
SCPI programming - ratio and delta ..................................................................... Programming examples ................................................................................. Applications .......................................................................................................... Testing superconductor materials .................................................................. 6 5-16 5-16 5-18 5-19 Buffer Buffer operations ..................................
9 Stepping and Scanning Step/Scan overview ................................................................................................ 9-3 Internal Stepping/Scanning (Channels 1 and 2) .............................................. 9-3 External Stepping/Scanning ............................................................................ 9-3 Front panel trigger models ...................................................................................... 9-4 Internal scanning ..........................
RS-232 interface reference .................................................................................. Sending and receiving data .......................................................................... Baud rate, flow control and terminator ........................................................ RS-232 connections ..................................................................................... Error messages ....................................................................................
15 Additional SCPI Commands DISPlay subsystem ............................................................................................... 15-3 :TEXT commands ......................................................................................... 15-3 FORMat subsystem .............................................................................................. 15-4 :DATA command .......................................................................................... 15-4 :BORDer command ...........
D Model 182 Emulation Commands E Example Programs Program examples .................................................................................................. Changing function and range .......................................................................... One-shot triggering ......................................................................................... Generating SRQ on buffer full ........................................................................
:MEASure[:]? ...................................................................................... What it does .................................................................................................... Limitations ..................................................................................................... When appropriate ........................................................................................... [:SENSe[1]]:DATA:FRESh? .........................................
List of Illustrations 1 Getting Started Figure 1-1 Figure 1-2 Figure 1-3 Model 2182 front panel ....................................................................................... 1-7 Model 2182 rear panel ...................................................................................... 1-11 Power module ...................................................................................................
6 Buffer Figure 6-1 Buffer locations .................................................................................................. 6-3 7 Triggering Figure 7-1 Figure 7-2 Figure 7-3 Figure 7-4 Figure 7-5 Figure 7-6 Figure 7-7 Figure 7-8 Figure 7-9 Figure 7-10 Front panel trigger model (without Stepping/Scanning) .................................... 7-3 Device action ...................................................................................................... 7-5 Rear panel pinout .......
12 Common Commands Figure 12-1 Figure 12-2 Figure 12-3 Figure 12-4 Standard event enable register .......................................................................... 12-5 Standard event status register ........................................................................... 12-7 Service request enable register ....................................................................... 12-13 Status byte register ........................................................................................
List of Tables 1 Getting Started Table 1-1 Table 1-2 Fuse ratings ....................................................................................................... 1-15 Factory defaults ................................................................................................. 1-17 2 Voltage and Temperature Measurements Table 2-1 Table 2-2 Table 2-3 Measurement channels ........................................................................................
10 Analog Output Table 10-1 Table 10-2 Analog output examples* ................................................................................. 10-3 SCPI commands - analog output ...................................................................... 10-6 11 Remote Operation Table 11-1 Table 11-2 Table 11-3 General bus commands and associated statements .......................................... 11-9 RS-232 connector pinout .............................................................................
F IEEE-488 Bus Overview Table F-1 Table F-2 Table F-3 Table F-4 Table F-5 Table F-6 IEEE-488 bus command summary ..................................................................... F-7 Hexadecimal and decimal command codes ...................................................... F-10 Typical addressed bus sequence ........................................................................ F-11 Typical addressed common command sequence .............................................. F-11 IEEE command groups .
Getting Started 1 Getting Started
1-2 Getting Started NOTE This User’s Manual supports both the Models 2182 and 2182A: References to the Model 2182 apply to both the Models 2182 and 2182A. References to the Model 2182/2182A apply to the Model 2182 with firmaware version A10 or higher, and the Model 2182A with firmware version C01 or higher. References to the Model 2182A applies to the Model 2182A with firmware version C01 or higher.
Getting Started 1-3 General information Warranty information Warranty information is located at the front of this manual. Should your Model 2182 require warranty service, contact the Keithley representative or authorized repair facility in your area for further information. When returning the instrument for repair, be sure to fill out and include the service form at the back of this manual to provide the repair facility with the necessary information.
1-4 Getting Started If an additional manual is required, order the appropriate manual package. The manual packages include a manual and any pertinent addenda. Options and accessories The following options and accessories are available from Keithley for use with the Model 2182. Cables, connectors, and adapters Models 2107-4 and 2107-30 Input Cable — Connect the Model 2182 Nanovoltmeter to DUT using one of these input cables.
Getting Started 1-5 Rack mount kits Model 4288-1 Single Fixed Rack Mount Kit — Mounts a single Model 2182 in a standard 19-inch rack. Model 4288-2 Side-by-Side Rack Mount Kit — Mounts two instruments (Models 182, 428, 486, 487, 2000, 2001, 2002, 2010, 2182, 2400, 2410, 2420, 6517, 7001) side-by-side in a standard 19-inch rack. Model 4288-4 Side-by-Side Rack Mount Kit — Mounts a Model 2182 and a 5.25-inch instrument (Models 195A, 196, 220, 224, 230, 263, 595, 614, 617, 705, 740, 775, etc.
1-6 Getting Started Nanovoltmeter features The Model 2182 is a 71⁄2-digit high-performance digital nanovoltmeter. It has two input channels to measure voltage and temperature. The measurement capabilities of the Model 2182 are explained in Section 2 of this manual (see “Measurement overview”). Features of the Model 2182 Nanovoltmeter include: • • • • • • • • • • • • • • Ratio — Provides comparison readings between two voltage inputs. Ratio performs V1/V2.
Getting Started 1-7 Front and rear panel familiarization Front panel summary The front panel of the Model 2182 is shown in Figure 1-1. This figure includes important abbreviated information that should be reviewed before operating the instrument.
1-8 Getting Started 2 Function and operation keys Top Row Un-shifted DCV1 DCV2 V1/V2 ACAL FILT REL TEMP1 TEMP2 Shifted MX+B % V1-V2 LSYNC TYPE OUTPUT AOUT TCOUPL Selects Channel 1 voltage measurement function. Selects Channel 2 voltage measurement function. Selects Ratio (Channel 1 voltage reading / Channel 2 voltage reading). Selects automatic gain calibration. Enables/disables filter for selected measurement function. Enables/disables relative for selected measurement function.
Getting Started 1-9 Bottom Row Un-shifted STEP SCAN SAVE RESTR DIGITS RATE EXIT ENTER Shifted CONFIG HALT GPIB RS232 CAL TEST Steps through channels; sends a trigger after each channel. Scans through channels; sends a trigger after last channel. Saves present configuration for power-on user default. Restores factory or user default configuration. Changes number of digits of reading resolution. Changes reading rate; number of power line cycles (PLC). Cancels selection, moves back to measurement display.
1-10 Getting Started 4 Display annunciators * (asterisk) ↔ (more) ))) (speaker) AUTO BUFFER CH1 CH2 CH1 and CH2 ERR FAST FILT HOLD LSTN MATH MED REAR REL REM SCAN SHIFT SLOW SRQ STAT STEP TALK TIMER TRIG Readings being stored in buffer. Indicates additional selections are available. Beeper on for limit testing. Autorange enabled. Recalling readings stored in buffer. Channel 1 input displayed. Channel 2 input displayed. Ratio (V1/V2) reading displayed. Questionable reading, or invalid cal step. Fast (0.
Getting Started 1-11 Rear panel summary The rear panel of the Model 2182 is shown in Figure 1-2. This figure includes important abbreviated information that should be reviewed before operating the instrument. Figure 1-2 Model 2182 rear panel 1 3 2 4 WARNING:NO INTERNAL OPERATOR SERVICABLE PARTS,SERVICE BY QUALIFIED PERSONNEL ONLY. MADE IN U.S.A.
1-12 Getting Started 1 ANALOG OUTPUT Provides a scaled non-inverting DC voltage. With analog output gain set to one, a full range input will result in a 1V analog output. 2 TRIGGER LINK Eight-pin micro-DIN connector for sending and receiving trigger pulses among connected instruments. Use a trigger link cable or adapter, such as Models 8501-1, 8501-2, 8502, and 8503. 3 RS-232 Connector for RS-232 operation. Use a straight-through (not null modem) DB-9 shielded cable.
Getting Started 1-13 Cleaning input connectors The two-channel LEMO connector on the front panel is used to connect the Model 2182 to external test circuits. This connector mates to the LEMO connector on the Model 2107 input cable or to the LEMO connector that is included with the Model 2182-KIT. The contacts of the LEMO connectors are made of copper. These copper-to-copper connections minimize thermal EMFs. However, exposed copper is susceptible to oxidation, which could cause measurement errors.
1-14 Getting Started Power-Up Line power connection Perform the following procedure to connect the Model 2182 to line power and turn on the instrument. 1. Check to be sure the line voltage setting on the power module (see Figure 1-3) is correct for the operating voltage in your area. If not, refer to the next procedure, “Setting line voltage and replacing fuse” on page 1-15. Operating the instrument on an incorrect line voltage may cause damage to the instrument, possibly voiding the warranty.
Getting Started 1-15 Setting line voltage and replacing fuse A rear panel fuse located next to the AC receptacle protects the power line input of the instrument. If the line voltage setting needs to be changed or the line fuse needs to be replaced, perform the following steps: WARNING 1. 2. Place the tip of a flat-blade screwdriver into the power module by the fuse holder assembly (see Figure 1-3). Gently push in and move to the left.
1-16 Getting Started Line frequency On power-up, the Model 2182 detects the line power frequency and automatically selects the proper line frequency setting. The line frequency setting can be checked using the following command: :SYSTem:LFRequency? The response message will be 50 or 60. The value 50 indicates that the line frequency is set for 50Hz (or 400Hz), while 60 indicates that it is set for 60Hz.
Getting Started 1-17 To restore factory or user settings: 1. 2. 3. NOTE Press RESTR. Use the and keys to display FACT (factory) or USER defaults. Press ENTER. The basic measurement procedure in the next section (Section 2) assumes factory defaults (Table 1-2). Reset the instrument to the factory default settings when following that step-by-step procedure.
1-18 Getting Started Table 1-2 Factory defaults (cont.) Setting Scanning Type Timer Channel 1 count Reading count TEMP1 and TEMP2 Digits Filter Analog filter Digital filter Count Mode Window Rate Reference junction Relative (REL) Sensor Thermocouple type Units Triggers Continuous Delay Control Source DCV1 and DCV2 Digits Filter Analog filter Digital filter Count Mode Window Hold Count Window Range Rate Relative (REL) Factory Default Off Internal Off 1 2 6 On Off On 10 Moving average 0.
Voltage and Temperature Measurements 2 Voltage and Temperature Measurements
2-2 Voltage and Temperature Measurements • • • • • • • Measurement overview — Explains the voltage and temperature measurement capabilities of the Model 2182. Performance considerations — Covers various aspects of operation that affect accuracy and speed. These include warm-up, ACAL (calibration), autozero, and LSYNC (line cycle synchronization). Includes the SCPI commands for remote operation. Connections — Covers test circuit connection to the Model 2182.
Voltage and Temperature Measurements 2-3 Measurement overview The Model 2182 provides two input channels for DC voltage and temperature measurements. Table 2-1 lists the measurements that can be performed by the two channels. NOTE Measurement queries are used to trigger and/or return readings. Details are provided in Section 7, Section 13, and Appendix H.
2-4 Voltage and Temperature Measurements NOTE The Model 2182 can also measure its internal temperature. Whenever the internal temperature changes more than 1 degree, an ACAL must be performed to maintain specified accuracy. See “Performance considerations, ACAL procedure” (in this section) for details. In order to make accurate temperature measurements, the thermocouple connections (reference junction) have to be maintained at a known temperature.
Voltage and Temperature Measurements 2-5 Performance considerations The following aspects of operation affect accuracy and speed. Warm-up After the Model 2182 is turned on, it must be allowed to warm up for at least 21⁄2 hours to allow the internal temperature to stabilize. After the warm-up period, an ACAL must be performed if the present internal temperature and TCAL differ by more than 1°C. TCAL is the internal temperature reading stored for the last ACAL (see “ACAL”).
2-6 Voltage and Temperature Measurements 3. Press ENTER. The message “ACAL” will be displayed while calibration is in process. It takes around five minutes to complete LOW-LVL ACAL and a little more than five minutes to complete FULL ACAL. When finished, the instrument returns to the normal display state. Measuring internal temperature Perform the following steps to measure the internal temperature of the Model 2182: 1. 2. 3. 4. 5. 6.
Voltage and Temperature Measurements 2-7 Front Autozero With Front Autozero for the front-end amplifier enabled (which is the default setting), the Model 2182 performs two A/D measurement cycles for each reading. The first one is a normal measurement cycle, and the second one is performed with the polarity of the amplifier reversed. This two-cycle, polarity-reversal measurement technique is used to cancel internal offsets in the amplifier.
2-8 Voltage and Temperature Measurements Controlling autozeroing modes For front panel operation, the two autozeroing modes are controlled from the SHIFT > CONFIG menu as follows: NOTE For remote programming, the commands to control the two autozeroing modes are listed in Table 2-2. 1. Press SHIFT and then CONFIG to display the present state of Front Autozero; Y = yes (enabled), N = no (disabled). To change the FRONT AZERO setting, use the or key to display Y or N.
Voltage and Temperature Measurements 2-9 Perform the following steps to enable or disable line cycle synchronization: 1. 2. 3. NOTE Press SHIFT and then LSYNC to display the present state of line synchronization (OFF or ON). Use or key to display “ON” or “OFF.” Press ENTER. The instrument returns to the normal display state. Line cycle synchronization is not available for integration rates <1 PLC, regardless of the LSYNC setting.
2-10 Voltage and Temperature Measurements SCPI programming - ACAL, Front Autozero, Autozero, LSYNC, and Low Charge Injection Table 2-2 SCPI commands - ACAL, Front Autozero, Autozero, LSYNC, and Low Charge Injection Commands For ACAL: :CALibration :UNPRotected :ACALibration :INITiate :STEP1 :STEP2 :DONE :TEMPerature? :SENSe :TEMPerature :RTEMperature? Description Default CALibration Subsystem: ACAL: Prepare 2182 for ACAL. Perform full ACAL (100V and 10mV). Perform low level ACAL (10mV only).
Voltage and Temperature Measurements 2-11 Programming examples - ACAL, Autozero, and LSYNC Program Example 1 — This program fragment performs low-level ACAL: NOTE: CALL CALL CALL CALL After sending the following commands, the :DONE and :INIT commands will not execute until calibration is completed. SEND(7,”:cal:unpr:acal:init”,status%) SEND(7,”:cal:unpr:acal:step2”,status%) SEND(7,”:cal:unpr:acal:done”,status%) SEND(7, “:init:cont on”, status%) ‘ ’ ‘ ‘ ‘ Prepares 2182 for ACAL.
2-12 Voltage and Temperature Measurements Connections WARNING A hazardous voltage condition exists at or above 42V peak. To prevent electric shock that could result in injury or death, NEVER make or break connections while hazardous voltage is present. CAUTION Exceeding the following limits may cause instrument damage not covered by the warranty: • Channel 1 HI and LO inputs have a maximum measurement capability of 120V peak.
Voltage and Temperature Measurements 2-13 Figure 2-2 Model 2107 input cable 2182 Red CHANNEL 1 LO HI HI Channel 1 Model 2107 ! HI LO CHANNEL 2 Input Cable Black 120V MAX LO Green HI Channel 2 12V MAX CAT I 350V PEAK ANY TERMINAL TO CHASSIS White LO Voltage Connections — Mechanically connect (clamp) the cleaned copper lugs of the cable to the cleaned copper connectors of the test circuit. For the test circuit, use clean #10 copper bus wire wherever possible.
2-14 Voltage and Temperature Measurements To make these customized connections, you can modify the supplied input cable, or you can use the LEMO connector that is included with the optional Model 2182-KIT. CAUTION Silver solder has a high temperature melting point. Take care not to damage the LEMO connector by applying excessive heat. Voltage only connections Single Channel Measurement Connections — Figure 2-4 shows typical connections to measure a DUT using a single channel.
Voltage and Temperature Measurements 2-15 Also note that channel voltage differential reduces the maximum measurement capability of Channel 2. Normally, Channel 2 can measure up to 12V. However, a 2V differential reduces the maximum measurement capability of Channel 2 to 10V. In Figure 2-5A, a >10V input to Channel 2 will cause an overflow condition. NOTE Channel 2 HI or LO cannot be more than 12V peak from Channel 1 LO.
2-16 Voltage and Temperature Measurements Figure 2-7 shows temperature only connections using an ice bath as a simulated reference junction. Note that the connection points for the input cable and the thermocouple wires are immersed in the ice bath.
Voltage and Temperature Measurements 2-17 Figure 2-9 shows the same test except that a simulated reference junction (ice bath) is used.
2-18 Voltage and Temperature Measurements Temperature configuration If you are going to perform temperature measurements, you have to configure the Model 2182 appropriately from the temperature configuration menu: Temperature configuration menu The items of the temperature configuration menu are explained as follows: • • • • UNITS — Select the desired units designator for temperature readings (˚C, ˚F, or K).
Voltage and Temperature Measurements 2-19 Measuring voltage and temperature NOTES The following procedure assumes factory default conditions (see Table 1-2 in Section 1). Details on using other settings and front panel operations are provided in Section 3 through Section 8 of this manual. Any time the internal temperature of the Model 2182 changes by 1˚C or more, the 10mV and 100V ranges will need to be calibrated (see “Performance considerations, ACAL procedure” for details).
2-20 Voltage and Temperature Measurements Nulling thermal EMFs The following procedure nulls out thermal EMFs using the Relative feature of the Model 2182. For more information on thermal EMFs, see “Low-level considerations; Thermal EMFs.” Details on Relative are provided in Section 4. 1. 2. 3. 4. 5. 6. Connect the test circuit but leave the source (voltage or current) disconnected or in stand-by. Select the appropriate voltage function; DCV1 or DCV2.
Voltage and Temperature Measurements 2-21 Programming Example - measure voltage and temperature The following program fragments will measure voltage on Channel 1 and temperature on Channel 2. Temperature is configured using a simulated reference junction (i.e., ice bath) and a type K thermocouple. ‘ Configure Temperature: CALL SEND(7,“:sens:temp:trans tc”,status%) CALL CALL CALL CALL ‘Select thermocouple ‘sensor. SEND(7,“:sens:temp:rjun:rsel sim”,status%) ‘Select simulated ‘reference.
2-22 Voltage and Temperature Measurements Low-level considerations For sensitive measurements, external considerations beyond the Model 2182 affect accuracy. Effects not noticeable when working with higher voltages are significant in nanovolt signals. The Model 2182 reads only the signal received at its input; therefore, it is important that this signal be properly transmitted from the source. Two principal factors that can corrupt measurements are thermal EMFs and noise induced by AC interference.
Voltage and Temperature Measurements 2-23 Applications Low-resistance measurements The Model 2182 can be used with a current source to measure resistances at levels well below the capabilities of most conventional instruments. The following paragraphs discuss lowresistance measurement techniques and include some applications to test switches.
2-24 Voltage and Temperature Measurements Compensating for thermal EMFs — Although the 4-wire measurement method minimizes the effects of lead resistances, other factors can affect low-resistance measurement accuracy. Thermal EMFs, and other effects can add an extraneous DC offset voltage (VOFFSET in Figure 2-10) to the measured voltage. The Relative feature of the Model 2182 can be used to null out the offset voltage.
Voltage and Temperature Measurements 2-25 High power switches — Heat is a factor in high power switching. As the temperature of the switch increases, so does the contact resistance. In Figure 2-12 heat is generated in the switch by sourcing a constant high current (i.e., 10A) through it.
2-26 Voltage and Temperature Measurements Standard cell comparisons Standard cell comparisons are conducted by measuring the potential difference between a reference and an unknown standard cell. All cell differences are determined in series opposition configuration. The positive terminals of the standard cells (V1 and V2) are connected to the HI and LO inputs of the nanovoltmeter, as shown in Figure 2-13A.
Voltage and Temperature Measurements 2-27 Heated Zener Reference and Josephson Junction Array comparisons The performance of a Heated Zener Reference can be analyzed by comparing it to a Josephson Junction (JJ) Array using both channels of the Model 2182. In a cryogenic environment, the JJ Array provides an output voltage in precise, stable 175µV steps. The test circuit for this application is shown in Figure 2-14. The JJ Array is adjusted until Channel 1 of the Model 2182 measures 0V ±10µV.
2-28 Voltage and Temperature Measurements
Range, Digits, Rate, and Filter 3 Range, Digits, Rate, and Filter
3-2 Range, Digits, Rate, and Filter • • • • Range — Provides details on measurement range selection for DCV1 and DCV2. Includes the SCPI commands for remote operation. Digits — Provides details on selecting display resolution for voltage and temperature measurements. Includes the SCPI commands for remote operation. Rate — Provides details on reading rate selection. Includes the SCPI commands for remote operation. Filter — Provides details on Filter configuration and control.
Range, Digits, Rate, and Filter 3-3 Range The selected range affects both accuracy of the voltage measurement as well as the maximum voltage that can be measured. The DCV1 function has five measurement ranges; 10mV, 100mV, 1V, 10V, and 100V. The DCV2 function has three measurement ranges; 100mV, 1V, and 10V. The range setting (fixed or AUTO) is remembered by each voltage function. NOTE The available voltage ranges for Ratio (V1/V2) depend on which channel is presently selected when Ratio is enabled.
3-4 Range, Digits, Rate, and Filter Autoranging To enable autoranging, press the AUTO key. The AUTO annunciator turns on when autoranging is selected. While autoranging is enabled, the instrument automatically selects the best range to measure the applied signal. Autoranging should not be used when optimum speed is required. Note that the AUTO key has no effect on temperature (TEMP1 and TEMP2). Up-ranging occurs at 120% of range, while down-ranging occurs at 10% of nominal range.
Range, Digits, Rate, and Filter 3-5 Digits The DIGITS key sets display resolution for the Model 2182. Display resolution for voltage readings can be set from 31⁄2 to 71⁄2 digits. For temperature readings, resolution can be set from 4 to 7 digits. You can have a separate digits setting for voltage and temperature functions. The digits setting for a voltage function applies to the other voltage function. For example, if you set DCV1 for 51⁄2 digits, DCV2 will also be set for 51⁄2 digits.
3-6 Range, Digits, Rate, and Filter Rate The RATE key selects the integration time of the A/D converter. This is the period of time the input signal is measured (also known as aperture). The integration time affects the amount of reading noise, as well as the ultimate reading rate of the instrument. The integration time is specified in parameters based on a number of power line cycles (NPLC), where 1 PLC for 60Hz is 16.67msec (1/60) and 1 PLC for 50Hz (and 400Hz) is 20msec (1/50).
Range, Digits, Rate, and Filter NOTE 3-7 For remote operation, the integration time can be set from 0.01 PLC to 60 PLC (50 PLC for 50Hz line power). Integration time can instead be set as an aperture time from 166.67µsec (200µsec for 50Hz) to 1 second. Perform the following steps to set the integration rate: 1. Select the desired function. 2. Press the RATE key until the desired number of power line cycles (PLC) is displayed. The appropriate annunciator will turn on (FAST, MED, or SLOW).
3-8 Range, Digits, Rate, and Filter Filter The Model 2182 has an analog filter and a digital filter. When Filter is enabled by pressing the FILT key (FILT annunciator on), it assumes the combination of analog and digital filter configuration for the present measurement function (DCV1, DCV2, TEMP, TEMP2). Filter state (enabled or disabled) and configuration is saved by each function.
Range, Digits, Rate, and Filter 3-9 Filter window — The digital filter uses a window to control filter threshold. As long as the input signal remains within the selected window, A/D conversions continue to be placed in the stack. If the signal changes to a value outside the window, the filter resets, and the filter starts processing again starting with a new initial conversion value from the A/D converter. The five window selections from the front panel are 0.01%, 0.
3-10 Range, Digits, Rate, and Filter Figure 3-2 Moving and repeating filters Conversion #10 #9 #8 #7 #6 #5 #4 #3 #2 Conversion #1 Reading #1 Conversion #11 #10 #9 #8 #7 #6 #5 #4 #3 Conversion #2 Reading #2 Conversion #12 #11 #10 #9 #8 #7 #6 #5 #4 Conversion #3 Reading #3 Reading #2 Conversion #30 #29 #28 #27 #26 #25 #24 #23 #22 Conversion #21 Reading #3 A.
Range, Digits, Rate, and Filter 3-11 Filter control and configuration The FILT key toggles the state of the Filter. When the Filter is enabled, the FILT annunciator is on. When disabled, the FILT annunciator is off. The analog and digital filters can be configured while the Filter is enabled or disabled. Perform the following steps to configure the Filter: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. Select the desired function (DCV1, DCV2, TEMP1, or TEMP2). Press SHIFT and then TYPE.
3-12 Range, Digits, Rate, and Filter SCPI programming - filter NOTE All the filter commands are part of the SENSe Subsystem. Table 3-4 SCPI commands - filter Commands For DCV1: :SENSe: :VOLTage [:CHANnel1] :LPASs :DFILter :WINDow :COUNt :TCONtrol [:STATe] Description SENSe Subsystem: Volts function: Channel 1 (DCV1): Enable or disable analog filter. Configure and control digital filter: Specify filter window (in %): 0 to 10. Specify filter count: 1 to 100.
Range, Digits, Rate, and Filter 3-13 Programming example The following program fragment configures the Filter for Channel 2 voltage (DCV2). It disables the analog filter and enables the digital filter (5% window, count 10, moving). ‘Analog Filter: CALL SEND(7,“:sens:volt:chan2:lpas off”,status%) ‘Disable analog filter.
3-14 Range, Digits, Rate, and Filter
Relative, mX+b, and Percent (%) 4 Relative, mX+b, and Percent (%)
4-2 Relative, mX+b, and Percent (%) • • Relative — Explains how to null an offset or establish a baseline value. Includes the SCPI commands for remote operation. mX+b and Percent (%) — Covers these two basic math operations, and includes the SCPI commands for remote operation.
Relative, mX+b, and Percent (%) 4-3 Relative Relative (rel) nulls an offset or subtracts a baseline reading from present and future readings. When a rel value is established, subsequent readings will be the difference between the actual input and the rel value. Displayed (Rel’ed) Reading = Actual Input - Rel Value Once a rel value is established for a measurement function, the value is the same for all ranges.
4-4 Relative, mX+b, and Percent (%) SCPI programming - relative Table 4-1 SCPI commands - relative Commands Description For DCVI and DCV2: :SENSe :VOLTage [:CHANnel1] :REFerence :STATe :ACQuire SENSe Subsystem: Volts function: Channel 1 (DCV1): Specify rel value: –120 to 120 (volts). Enable or disable relative. Use input signal as rel value. :CHANnel2 :REFerence :STATe :ACQuire Channel 2 (DCV2): Specify rel value: –12 to 12 (volts). Enable or disable relative.
Relative, mX+b, and Percent (%) 4-5 Programming examples - relative Program Example 1 — This program fragment shows how to null out zero offset for the DCV1 function. Be sure to short the Channel 1 input. CALL SEND(7,“:syst:pres”,status%) CALL SEND(7,“:fetch?”,status%) reading$ = SPACE$(80) CALL ENTER(reading$,length%,7,status%) CALL SEND(7,“:sens:volt:ref:acq”,status%) CALL SEND(7,“:sens:volt:ref:stat on”,status%) ‘Selects DCV1 and enables ‘autorange. ‘Fetches Channel 1 offset. ‘Gets offset reading.
4-6 Relative, mX+b, and Percent (%) mX+b and percent (%) mX+b This math operation manipulates normal display readings (X) mathematically according to the following calculation: Y = mX+b where: X is the normal display reading m and b are user-entered constants for scale factor and offset Y is the displayed result To configure and control the mX+b calculation, perform the following steps: 1. Press SHIFT and then MX+B to display the present scale factor: M: +1.0000000 ^ 2. 3.
Relative, mX+b, and Percent (%) 4-7 Percent (%) This math function determines percent deviation from a specified reference value. The percent calculation is performed as follows: Input – Reference Percent = ––––––––––––––––– × 100% Reference where: Input is the normal display reading Reference is the user entered constant Percent is the displayed result To configure and control the percent calculation, perform the following steps: 1.
4-8 Relative, mX+b, and Percent (%) SCPI programming - mX+b and percent Table 4-2 SCPI commands - mX+b and percent Commands :CALCulate :FORMat :KMATh :MMFactor :MBFactor :MUNits :PERCent :ACQuire :STATe :DATA [:LATest]? :FRESh? Description Default Select calculation; NONE, MXB or PERCent. Path to configure mX+b and Percent: Specify scale factor (M) for mX+b: –100e6 to 100e6. Specify offset (B) for mX+b: -100e6 to 100e6.
Ratio and Delta 5 Ratio and Delta
5-2 Ratio and Delta NOTE When using the Model 2182/2182A with the Model 6220 or 6221 Current Source, enhanced Delta and Differential Conductance measurements can be performed. When using the Model 2182A with the Model 6220 Current Source, Pulsed Delta measurements can be performed. See Section I for details on enhanced Delta, Pulsed Delta, and Differential Conductance. • • • • Ratio — Covers the Ratio calculation, and the effects of Filter, Rel and Ranging.
Ratio and Delta Step 1 5-3 Connect voltages to be measured to the Model 2182. Details on connecting the Model 2182 to the voltages to be measured are provided in Section 2 (see “Connections”). WARNING A hazardous voltage condition exists at or above 42V peak. To prevent electric shock that could result in injury or death, NEVER make or break connections while hazardous voltage is present.
5-4 Ratio and Delta Filter, Rel, and Ranging considerations Filter considerations As explained in Section 3, a unique Filter configuration can be established for each voltage channel. However, the Filter configuration for Channel 1 is applied to both channels when Ratio is enabled. The Filter state and configuration for Channel 2 are ignored. Channel 1 Filter has priority because it has the most sensitive measurement range (10mV) and may therefore be configured to provide more filtering than Channel 2.
Ratio and Delta NOTE 5-5 The previous calculation shows Filter enabled. If Filter is not used, remove the “Filt” component from the calculation. When Ratio is enabled, the state (on or off) of the REL annunciator depends on which measurement function was last selected. If on DCV1 when Ratio is enabled, the state of the REL annunciator (on or off) will indicate the state (enabled or disabled) of Rel for DCV1.
5-6 Ratio and Delta Delta Delta provides the measurements and calculation for the DC current-reversal technique to cancel the effects of thermal EMFs in the test leads. Each Delta reading is calculated from two voltage measurements on Channel 1; one on the positive phase of an alternating current source, and one on the negative phase. Basic Delta Calculation: V1t1 – V1t2 Delta = -------------------------------2 where:V1t1 is the voltage measurement on the positive phase of the current source.
Ratio and Delta 5-7 Figure 5-1 Test circuit using constant current source VTHERM 10µV HI 1mA 2182 CH 1 + VDUT = 100µV DUT 0.1Ω V LO – V2182 = 10µV + 100µV = 110µV A. Positive Current Source VTHERM HI 1mA 2182 CH 1 10µV – VDUT = –100µV DUT 0.1Ω V LO + V2182 = 10µV – 100µV = –90µV B. Negative Current Source Figure 5-1B shows what happens when the current is reversed. The measurement by the Model 2182 still includes the 10µV of thermal EMF, but the voltage across the DUT is now negative.
5-8 Ratio and Delta To use the DC current-reversal technique, replace the constant current source with a bipolar current source as shown in Figure 5-2. The current source will alternate between +1mA and –1mA. When using Delta, the Model 2182 performs the first voltage measurement (V1t1) while sourcing +1mA.
Ratio and Delta 5-9 Selecting Delta Delta is selected by pressing the SHIFT key and then the V1-V2 key. The “(Vt1-Vt2) / 2” message appears briefly before displaying the result of the calculation. Delta is disabled by selecting a single measurement function (DCV1, DCV2, TEMP1, or TEMP2) or by selecting Ratio.
5-10 Ratio and Delta When a growing-amplitude current is required, the custom sweep can be configured to include all the current values required for the test. For example, assume the test requires two Delta measurements at each of three current levels; 1mA, 2mA, and 5mA.
Ratio and Delta 5-11 Figure 5-3 Delta measurement connections 8501 Trigger Link Cable 2182 CH 1 SourceMeter HI DUT 0.1Ω LO Step 3 Configure the trigger model of the SourceMeter. The menu structure to configure triggers is accessed by pressing CONFIG and then TRIG.
5-12 Ratio and Delta Step 4 Set up the SourceMeter to source current and measure voltage. A. On the SourceMeter, select Source I and Measure V. B. Select an appropriate current source range. For example, if your current reversal values are going to ±1mA, select the 1mA source range. C. Press SPEED and select FAST. SourceMeter measurements are not used in this test, but it must run as fast as possible to avoid synchronization problems with the Model 2182.
Ratio and Delta Step 8 5-13 Turn on the SourceMeter output and reset the trigger model. A. Turn on the output by pressing the OUTPUT ON/OFF key (“ARM” annunciator turns on). B. Reset the trigger model as follows: 1. Press CONFIG and then TRIG to access the trigger configuration menu. Step 9 2. Select HALT to place the SourceMeter in the idle state (“ARM” annunciator turns off). 3. Press EXIT to return to the normal display. Set up the Model 2182 to store readings in the buffer (optional).
5-14 Ratio and Delta Model 2182 and SourceMeter trigger synchronization The timing diagram in Figure 5-4 shows trigger synchronization between the SourceMeter and the Model 2182 for a 2-point custom sweep. As shown in the timing diagram, the SourceMeter will output a trigger after every source sweep point, and the Model 2182 will output a trigger after every A/D conversion. Figure 5-4 Triggering timing diagram One Delta Measurement +1mA P0000 SourceMeter Output –1mA P0000 ... ...
Ratio and Delta 5-15 Filter considerations The filter configuration for DCV1 is applied separately to each measurement phase (V1t1 and V1t2) of the Delta process. NOTE The repeating filter cannot be used for Delta measurements. When Delta is selected, the Filter will automatically switch to the moving filter if the repeating filter was enabled. Moving filter — After filtering yields a reading for V1t1, an output trigger is sent. After filtering yields a reading for V1t2, another output trigger is sent.
5-16 Ratio and Delta SCPI programming - ratio and delta Table 5-1 SCPI commands - ratio and delta Commands Description :SENSe[1] SENSe Subsystem: :FUNCtion Select voltage function; ‘VOLTage’. :CHANnel Select range control channel; 1 or 2. :VOLTage[:DC] Path to configure DC volts: Default VOLT :RATio Enable or disable Ratio (V1/V2). OFF :DELTa Enable or disable Delta. Not valid with TEMP1 or TEMP2 selected. OFF Enable or disable Front Autozero.
Ratio and Delta 5-17 Delta programming example — The following program fragment uses a SourceMeter (SM) with the Model 2182 to perform Delta measurements. External triggering (via Trigger Link) is used to synchronize the source-measure operations between the two instruments. Also, Front Autozero is disabled to double the speed of Delta. Three Delta measurements will be performed; one at a source value of 10µA, one at 20µA, and one at 50µA. The three readings will be stored in the buffer of the Model 2182.
5-18 Ratio and Delta Applications Calibrating resistor network dividers Ratio can be used to calibrate resistor network dividers. The 1:10 divider network in Figure 5-5 is made up of nominal resistances of 1kΩ and 10kΩ. The 1kΩ resistance is the result of the parallel combination of the 2kΩ pot and the 2kΩ resistor. The pot provides fine tuning of the network.
Ratio and Delta 5-19 For even greater precision, the Relative feature of the Model 2182 can be used to null out thermal EMFs, which can corrupt low voltage measurements. Use Rel as follows: 1. 2. 3. While displaying the Ratio result, disconnect the current source from the network. Press the REL key on the Model 2182. The voltages at each input, which are thermal EMFs, are nulled out. Reconnect the current source and take the result of Ratio from the display.
5-20 Ratio and Delta Superconductor Application #1 - fixed current A typical test on a superconductor sample (DUT) is to vary the magnetic field (H) while maintaining a fixed current (I) through the DUT. Such a test system is shown in Figure 5-6. A Keithley SourceMeter (Model 2400, 2410, or 2420) is used to source current through the DUT and the Model 2182 measures the voltage across the DUT. Keep in mind that the I-Source of the SourceMeter is a constant current source.
Ratio and Delta 5-21 Figure 5-7 H-V Curve (Fixed I) Fixed I Measure V Magnetic Field (H) Delta measurements — As previously explained, the DC current reversal measurement technique must be used to cancel the effects of thermal EMFs in the test leads. By configuring a custom sweep, the SourceMeter can function as a bipolar, fixed amplitude source. For example, if the test requires a fixed current of 1mA, the custom sweep can be configured to alternate between +1mA and -1mA (see Figure 5-8).
5-22 Ratio and Delta Superconductor Application #2 - fixed magnetic field Another typical test on a superconductor sample (DUT) is to source an increasing-amplitude current (I) through the DUT, while maintaining the magnetic field (H) at a fixed level. The I-V curve in Figure 5-9 shows that the measured voltage across the DUT remains at ~0V for low currents (I). This is the flat portion of the curve where the DUT remains at 0Ω.
Ratio and Delta 5-23 Figure 5-10 Test circuit—Fixed H (Vary I) 2182 #1 CH 1 HI V LO RREF 1mA 100Ω HI SourceMeter Source ±I 2182 #2 CH 1 Thermal EMFs V 30´ Cables LO H DUT <4K Cryostat The readings in the buffer of Model 2182 #1 correspond to the current sweep values. You can then use the buffer location numbers to reference DUT readings to current amplitudes: Model 2182 #1 Buffer Model 2182 #2 Buffer RDG NO. 1 = 1mV ⇒ 10µA RDG NO. 2 = 2mV ⇒ 20µA RDG NO. 3 = 5mV ⇒ 50µA RDG NO.
5-24 Ratio and Delta To check measurement repeatability, you may wish to perform more than one Delta measurement at each current amplitude. In Figure 5-11, the SourceMeter outputs five bipolar steps for each amplitude. The result will be five Delta measurements for each amplitude. When configuring the custom sweep, ±10µA would be assigned to the first 10 points of the sweep, ±20µA would be assigned to the next 10 points, and ±50µA would be assigned to the last 10 points.
Ratio and Delta 5-25 Figure 5-11 SourceMeter output—30-point custom sweep P20 +50µA P10 +20µA +10µA P0 P2 P4 P6 P12 P14 P16 P22 P24 P26 P28 P18 P8 ...
5-26 Ratio and Delta Trigger link connections — External triggering is used to synchronize source-measure operations among the instruments. The SourceMeter must trigger both Model 2182s to achieve simultaneous measurements. In turn, only one of the Model 2182s must trigger the SourceMeter to output the next source value. The trigger link connections required for this application are shown in Figure 5-12. Notice that the output trigger (VMC) required from the Model 2182s is provided by unit #1.
Buffer 6 Buffer
6-2 Buffer • • Buffer operations — Explains how to store and recall readings including buffer statistics (minimum, maximum, peak-to-peak, average, and standard deviation). SCPI programming — Covers the SCPI commands used to control buffer operations. Buffer operations The Model 2182 has a buffer to store from two to 1024 readings and units. It also stores the channel number for step/scan readings and overflow readings.
Buffer 6-3 Recall Perform the following steps to view stored readings and buffer statistics: 1. 2. 3. Press RECALL. The BUFFER annunciator turns on to indicate that stored readings are being displayed. The arrow annunciator (↔) also turns on to indicate that additional data is available for viewing. As shown in Figure 6-1, use the RANGE and keys, and the cursor and keys to navigate through the reading numbers, reading values, and buffer statistics.
6-4 Buffer Buffer statistics • • MIN and MAX provides the minimum and maximum readings stored in the buffer. It also indicates the buffer location of these readings. The Peak-to-Peak reading is the absolute value of the difference between the MAX and MIN readings. It is calculated as follows: Peak-to-Peak = |MAX - MIN| • Average is the mean of the buffer readings. Mean is calculated as follows: n ∑ Xi =1 y = i---------------n where: Xi is a stored reading. n is the number of stored readings.
Buffer 6-5 SCPI programming - buffer Buffer commands are summarized in Table 6-1. TRACe subsystem commands are used to store and recall readings in the buffer, and CALCulate2 commands are used to obtain statistics from the buffer data. Additional information on these commands is provided after the table. Table 6-1 SCPI commands - buffer Commands :TRACe :CLEar :FREE? :POINts :FEED :CONTrol :DATA? Description TRACe Subsystem: Clear readings from buffer.
6-6 Buffer Programming example The following program fragment stores 20 readings into the buffer and then calculates the mean average on the buffer readings: ‘ Store Readings: CALL SEND(7,“:trac:poin 20”,status%) CALL SEND(7,“:trac:feed sens”,status%) CALL SEND(7,“:trac:feed:cont next”, status%) CALL SEND(7,“:trac:data?”,status%) reading$ = SPACE$(80) CALL ENTER(reading$, length%, 7, status%) PRINT reading$ ‘ Calculate Mean of Buffer Readings: CALL SEND(7,“:calc2:form mean”,status%) CALL SEND(7, “:calc2:s
Triggering 7 Triggering
7-2 Triggering • • • • Trigger model — Explains the various components of the front panel trigger model, which controls the triggering operations of the instrument. Reading hold — Explains the Reading Hold feature which is used to screen out readings that are not within a specified reading window. External triggering — Explains external triggering which allows the Model 2182 to trigger other instruments, and be triggered by other instruments.
Triggering 7-3 Trigger model NOTE Additional information on measurement query commands to trigger and/or return readings are provided in Section 13 and Appendix H. The flowchart in Figure 7-1 summarizes triggering as viewed from the front panel. It is called a trigger model because it is modeled after the SCPI commands used to control triggering. Note that for stepping and scanning, the trigger model has additional control blocks. These are described in Section 9.
7-4 Triggering Control source and event detection The control source holds up operation until the programmed event occurs and is detected. The control sources are described as follows: • • Immediate — With this control source, event detection is immediately satisfied allowing operation to continue. External — Event detection is satisfied for any of the following three conditions: • An input trigger via the Trigger Link line EXT TRIG is received. • The front panel TRIG key is pressed.
Triggering 7-5 Device action The primary device action is a measurement. However, the device action block could include the following additional actions (refer to Figure 7-2): Figure 7-2 Device action From Delay block of Figure 7-1 To Output Trigger block of Figure 7-1 Rdg Filter • • • Hold Chan DEVICE ACTION Filtering — If the repeating filter is enabled, the instrument samples the specified number of reading conversions to yield single filtered reading.
7-6 Triggering Reading hold (autosettle) With hold enabled (HOLD annunciator on), the first processed reading becomes the “seed” reading and operation loops back within the device action block. After the next reading is processed, it is checked to see if it is within the selected hold window (0.01%, 0.1%, 1%, 10%) of the “seed” reading. If the reading is within the window, operation again loops back within the device action block.
Triggering 7-7 External triggering The EX TRIG key selects triggering from two external sources: trigger link and the TRIG key. When EX TRIG is pressed, the TRIG annunciator lights and dashes are displayed to indicate the instrument is waiting for an external trigger. From the front panel, press the TRIG key to trigger a single reading. Pressing the EX TRIG key again toggles back to continuous triggers.
7-8 Triggering External trigger The EXT TRIG input requires a falling-edge, TTL-compatible pulse with the specifications shown in Figure 7-4. In general, external triggers can be used to control measure operations. For the Model 2182 to respond to external triggers, the trigger model must be configured for it. Figure 7-4 Trigger link input pulse specifications (EXT TRIG) Triggers on Leading Edge TTL High (2V-5V) TTL Low (<0.
Triggering 7-9 External triggering example In a typical test system, you may want to close a channel and then measure the DUT connected to the channel with the Model 2182. Such a test system is shown in Figure 7-6, which uses a Model 2182 to measure eight DUTs switched by a Model 7168 Nanovolt Scanner Card in a Model 7001/7002 Switch System. See Section 9 for details on external scanning.
7-10 Triggering For this example, the Models 2182 and 7001/7002 are configured as follows: Model 2182: Factory defaults restored (accessed from SHIFT-SETUP) External scanning, channels 1 - 8, no timer, 8 readings (accessed from SHIFT-CONFIG) External triggers (accessed from EX TRIG) Model 7001 or 7002: Factory defaults restored Scan list = 1!1-1!8, Number of scans = 1 Channel spacing = TrigLink To run the test and store readings in the Model 2182 with the unit set for external triggers, press STEP or SC
Triggering 7-11 A. Pressing EX TRIG then STEP or SCAN on the Model 2182 places it at point A in the flowchart, where it is waiting for an external trigger. B. Pressing STEP on the Model 7001/7002 takes it out of the idle state and places operation at point B in the flowchart. C. For the first pass through the model, the scanner does not wait at point B for a trigger. Instead, it closes the first channel. D. After the relay settles, the Model 7001/7002 outputs a Channel Ready pulse.
7-12 Triggering External triggering with BNC connections An adapter cable is available to connect the micro-DIN Trigger Link of the Model 2182 to instruments with BNC trigger connections. The Model 8503 DIN to BNC Trigger Cable has a micro-DIN connector at one end and two BNC connectors at the other end. The BNC cables are labeled VMC (trigger line 1) and EXT TRIG (trigger line 2).
Triggering 7-13 SCPI programming - triggering Trigger model (remote operation) The following paragraphs describe how the Model 2182 operates for remote operation. The flowchart in Figure 7-10 summarizes operation over the bus. The flowchart is called the trigger model because operation is controlled by SCPI commands from the Trigger subsystem. Key SCPI commands are included in the trigger model.
7-14 Triggering Idle and initiate The instrument is considered to be in the idle state whenever operation is at the top of the trigger model. As shown in Figure 7-10, initiation needs to be satisfied to take the instrument out of idle. While in the idle state, the instrument cannot perform any measure or step/scan operations.
Triggering 7-15 Trigger model operation Once the instrument is taken out of idle, operation proceeds through the trigger model down to the device action. In general, the device action includes a measurement and, when stepping/ scanning, closes the next channel. Control source — As shown in Figure 7-10, a control source is used to hold up operation until the programmed event occurs.
7-16 Triggering Triggering commands Commands for triggering are summarized in Table 7-2. Information not covered in the table or in “Trigger model (GPIB operation)” is provided after the table. The Ref column provides reference for this information. Table 7-2 SCPI commands - triggering Commands :ABORt :INITiate [:IMMediate] :CONTinuous :FETch? :READ? Description Reset trigger system. Initiation: Initiate one trigger cycle. Enable or disable continuous initiation. Request the last reading(s).
Triggering 7-17 Reference: A. B. C. D. E. F. G. H. I. J. ABORt — With continuous initiation disabled, the 2182 goes into the idle state. With continuous initiation enabled, operation continues at the top of the trigger model. INITiate — Whenever the instrument is operating within the trigger model, sending this command causes an error and will be ignored. INITiate:CONTinuous — With continuous initiation enabled, you cannot use the READ? command or set sample count (SAMPle:COUNt) greater than one.
7-18 Triggering
Limits 8 Limits
8-2 Limits • • • Limit operations — Explains Limit 1 and Limit 2 testing operations. SCPI programming — Covers the SCPI commands for remote operation. Application — Provides an application that sorts resistors by tolerances.
Limits 8-3 Limit operations Limit operations set and control the values that determine the HI/IN/LO status of subsequent measurements. The limit test is performed on the result of an enabled Rel, mX+b, or Percent operation. There are two sets of limits. Limit 1 uses high and low limits (HI1 and LO1) as does Limit 2 (HI2 and LO2). However, the HI/IN/LO status message only applies to Limit 1.
8-4 Limits Setting limit values Use the following steps to enter high and low limit values: 1. Press the Limits VALUE key to view the present HI1 limit value: HI1:+1.000000 ^ 2. 3. To change the HI1 limit, use the cursor keys ( and ) and the manual range keys ( and ) to display the desired value. Move the cursor to the rightmost position (^) and use the ( and ) keys to move the decimal point. Note that with the cursor on the polarity sign, pressing or toggles the polarity of the value.
Limits 8-5 SCPI programming - limits For remote operation, the testing capabilities of Limit 1 and Limit 2 are the same. Limit 1 and/or Limit 2 can be enabled. The commands to configure and control limit testing are listed in Table 8-1. NOTE When testing limits remotely, keep in mind that the front panel HI/IN/LO status messages only apply to Limit 1. Also, if the front panel beeper is set for OUTSIDE or INSIDE, it will operate according to its front panel definition as previously explained.
8-6 Limits NOTES 1. The fail message (“0”) for a limit test indicates that the reading is outside the specified limits. 2. With auto clear enabled, the fail message (“0”) is cleared when the instrument goes back into the idle state. If programmed not to go back into idle, you can manually clear the fail condition by sending the CLEar[:IMMediate] command. With auto clear disabled, the fail condition will have to be cleared manually. 3.
Limits 8-7 Application Sorting resistors Limits can be used to sort resistors. Figure 8-2 shows a basic setup to test 10Ω resistors. The Model 220 is used to source a constant 1mA through the resistor and the Model 2182 measures the voltage drop. Figure 8-2 Setup to test 10Ω resistors 1mA HI CH 1 DCV1 Model 220 Current Source 10Ω LO HI Test Circuit CH 2 LO 2182 For this application, the idea is to sort a batch of 10Ω resistors into three bins.
8-8 Limits Figure 8-3 Limits to sort 10Ω resistors (1%, 5%, and >5%) Beep (low pitch) No Beep Beep (normal pitch) LO -9.5mV LO2 Beep (low pitch) IN -9.9mV LO1 No Beep HI 0 +10.1mV HI1 +10.5mV HI2 Limit 1 (1%) Limit 2 (5%) Beeper Mode: INSIDE Front panel operation — For front panel operation, the INSIDE beeper mode must be used. A normal pitch beep and the message “IN” indicates that the resistor is within the 1% tolerance limit (see Figure 8-3). This 1% resistor belongs in Bin 1.
Stepping and Scanning 9 Stepping and Scanning
9-2 Stepping and Scanning • • • • • • Step/Scan overview — Summarizes the stepping and scanning operations. Front panel trigger models — Uses the trigger model to illustrate how stepping and scanning operates. Stepping/Scanning controls — Covers the front panel keys used to configure and control stepping/scanning. Stepping/Scanning examples — Provides examples for internal stepping and scanning, and external scanning. SCPI programming — Covers the SCPI commands used for stepping and scanning.
Stepping and Scanning 9-3 Step/Scan overview The Model 2182 can step or scan its two input channels or be used with external scanner cards installed in switching mainframes such as Models 707, 7001, and 7002. The following paragraphs summarize the various aspects of stepping/scanning using the Model 2182. NOTE Step and Scan operations are illustrated by trigger models (see “Front panel trigger models” in this section).
9-4 Stepping and Scanning Front panel trigger models The front panel trigger models for stepping and scanning are shown in Figure 9-1 and Figure 9-2. These are expansions of the basic front panel trigger model that is presented and explained in Section 7 (see Figure 7-1). The following discussions focus on the stepping and scanning operations. Be sure to refer to Section 7 for additional information on the various components of trigger models.
Stepping and Scanning Figure 9-1 Front panel triggering (internal scanning) Idle No Yes Control Source Another Scan? Trigger Counter Event Detection Output Trigger Immediate External Timer No Yes Another Reading ? Sample Counter Delay Device Action Figure 9-2 Front panel triggering (other step/scan operations) Idle No Yes Control Source Immediate External Timer Another Reading ? Event Detection Output Trigger Delay Device Action Trigger Counter (Reading Count) 9-5
9-6 Stepping and Scanning Other Stepping/Scanning operations • • • • • Control source: • Immediate — With immediate triggering, event detection occurs immediately allowing operation to drop down to the next trigger model block (Delay). • Timer — The timer is used to set a time interval between channels in a step/scan cycle. When STEP or SCAN is pressed, the timer starts and event detection occurs immediately allowing operation to drop down to Delay.
Stepping and Scanning 9-7 Step/Scan configuration Internal Stepping/Scanning The settings for internal stepping and scanning are explained as follows: Timer — The maximum timer interval is 99H:99M:99.999S (Hour:Minute:Second format). Channel 1 Count — This specifies the number of measurements to be performed while on Channel 1. Keep in mind that for each step/scan cycle, only one measurement is performed on Channel 2. Channel 1 Count can be set from 1 to 1023.
9-8 Stepping and Scanning External Stepping/Scanning The settings for external stepping/scanning are explained as follows: Min/Max Values — These two values specify the beginning and ending channels for the step/scan list. Valid values for Min is 1 to 799, and valid values for Max is 2 to 800. However, the Max value must be larger than the Min value. Timer — The maximum timer interval is 99H:99M:99.999S (Hour:Minute:Second format).
Stepping and Scanning Operation: 9-9 When the SCAN key is pressed, operation proceeds to Device Action where a measurement on Channel 2 is performed. The sample counter is decremented to 4 causing operation to loop back to Device Action for a measurement on Channel 1. Operation loops back to Device Action three more times to complete the scan cycle. After the scan cycle, the trigger counter is decremented to 1 and an output trigger is sent.
9-10 Stepping and Scanning External scanning Figure 9-3 summarizes the front panel operations to configure a scan for the “External triggering example” provided in Section 7. In that example, the Model 2182 is used to scan and measure eight DUTs switched by a Model 7168 Nanovolt Scanner card installed in a Model 7001/7002 Switch System. Figure 7-6 and Figure 7-7 show the signal and trigger connections, while Figure 7-8 shows trigger model operation for the test.
Stepping and Scanning Figure 9-3 External scanning example with Model 7001 Model 7001 (from “reset setup”) 1 SCAN CHANNELS 2 CONFIGURE SCAN CHAN-CONTROL CHANNEL-SPACING TRIGLINK ASYNCHRONOUS CHAN-COUNT 8 SCAN-CONTROL SCAN-COUNT 1 Model 2182 (from “factory setup”) 1!1-1!8 3 SHIFT-CONFIG TYPE:EXT MIN CHAN: 001 MAX CHAN: 008 TIMER? OFF RDG CNT: 0008 ENTER 4 5 6 EX TRIG STEP or SCAN STEP 7 RECALL (8 readings) , , , EXIT 9-11
9-12 Stepping and Scanning SCPI programming - stepping and scanning Commands to scan are listed in Table 9-1. Notice that many commands from the TRIGger Subsystem are used for scanning. See Section 7 for details on triggering.
Stepping and Scanning 9-13 Programming example The following program fragment performs a five measurement internal scan. The five readings are stored in the buffer and displayed on the computer CRT. CALL CALL CALL CALL CALL SEND(7,“*rst”,status%) SEND(7,“:samp:coun 5”,status%) SEND(7,“:rout:scan:int:cco 4”,status%) SEND(7,“:rout:scan:lsel int”,status%) SEND(7,“:read?”,status%) reading$ = SPACE$ (80) CALL ENTER (reading$,length%,7,status%) PRINT reading$ 'Restore *RST defaults. 'Set sample count to 5.
9-14 Stepping and Scanning Application — I-V curves using internal scan SCAN for IV curves [Measure V, sweep I, constant H (magnetic field) or T (temperature)] SCAN can be used to measure V, while sweeping the current through a sample with a constant magnetic field or a constant temperature.
Stepping and Scanning 9-15 Set up 2182 Restore factory defaults Filters: off Rate: 1plc Ch1: 10mV Ch2: 1V Ext Trigger: on Delay: Set to time needed for cable settling Config SCAN: INT Timer off Ch1 Count 3 ; Note Ch1 will store 3 readings / 2400 programmed current level. Ch2 will store 1 reading / 2400 programmed current level.
9-16 Stepping and Scanning Set up 2400 Menu: Savesetup: Global: Reset: Bench Meas: V Source: I Config Trig: ARM-LAYER: ARM-IN: IMMEDIATE ARM-OUT : LINE: #3 : EVENTS: TRIG-LAYER-DONE= OFF TRIG-LAYER: TRIGGER-IN: TRIGGER-LINK: #1: EVENT DETECT BYPASS NEVER: TRIGGER IN EVENTS: SOURCE= ON all others off TRIG-LAYER: TRIGGER-OUT: LINE: #2 : EVENTS :TRIGGER OUT EVENTS: SOURCE = ON, all others off. : COUNT 12 Config Sweep: TYPE: CUSTOM : #-POINTS: 12 : ADJUST-POINTS: see waveform : COUNT: INFINITE Speed: 0.
Stepping and Scanning 9-17 A loop program can be written to extract the data as follows: ' This is for Channel 2 Data’ Let NumRdgsPerStep = 4 ; 1 Ch2 and 3 Ch1 readings stored in the buffer / 2400 current level. Let CalcRdgs = 6 ; Total number of positive or negative current levels out of the 2400.
9-18 Stepping and Scanning AsciiRdgsBuf$ = SPACE$(18 * NumRdgs) 'represents the string of buffer response DIM Readings!(1 TO NumRdgs) 'array of the 48 individual readings in 'numerical representation form - converted from 'ASCII CALL send(Addr, "TRACE:DATA?", status%) 'ask 2182 for the buffer response CALL enter(AsciiRdgsBuf$, length%, Addr, status%) 'read in buffer response ' Start Parsing the data readings...
Stepping and Scanning FOR j = 1 TO (CalcReadings) Chan2! = Readings!(k%) - Reading!(k% + NumRdgsPerStep) Chan2! = Chan2! / 2 DataCH2$(j) = STR$(Chan2!) CH1pos! = 0! CH1neg! = 0! FOR i = 1 TO (NumRdgsPerStep - 1) CH1pos! = CH1pos! + Reading!(k% + i) CH1neg! = CH1neg! + Reading!(k% + i + NumRdgsPerStep) NEXT i Chan1! = ((CH1pos! - CH1neg!) / ((NumRdgsPerStep - 1) * 2)) DataCH1$(j) = STR$(Chan1!) k% = k% + (NumRdgsPerStep * 2) NEXT j 'Printing results to a file OPEN "chan1.xls" FOR OUTPUT AS #1 OPEN "chan2.
9-20 Stepping and Scanning
Analog Output 10 Analog Output
10-2 Analog Output • • • Overview — Covers the capabilities of the Analog Output. Operation — Explains how to configure and control the Analog Output. SCPI programming — Covers the SCPI commands associated with the Analog Output.
Analog Output 10-3 Overview The ANALOG OUTPUT provides a scaled, non-inverting voltage output up to ±1.2V. It is typically used to drive a chart recorder. The Analog Output voltage is calculated as follows: Analog Output = (Gain × Rdg/Rng) – Offset where: NOTE Gain is the user entered gain factor. Rdg is the reading on the Model 2182. Rng is the measurement range. Offset is the user entered offset value.
10-4 Analog Output Temperature The analog output voltage for temperature measurements depends on thermocouple type and the selected units (°C, °F, or K). The 1.2V analog output is scaled to the maximum positive temperature reading. For example, the measurement range for the Type J thermocouple is -200°C to +760°C. For a 760°C reading, the analog output voltage will be 1.2V, and for a -200°C reading, the analog output voltage will be –0.316V.
Analog Output 10-5 Operation Analog output connections The analog output is accessed from the rear panel BNC connector that is labeled “ANALOG OUTPUT.” This connector requires a cable that is terminated with a standard male BNC connector. Output resistance — The output resistance of Analog Output is 1kΩ ±5%. To minimize the effects of loading, the input resistance of the device connected to Analog Output should be as high as possible.
10-6 Analog Output SCPI programming - analog output Commands for analog output are summarized in Table 10-2. Additional information on these commands follows the table. The Ref column in the table provides reference for this information. Table 10-2 SCPI commands - analog output Commands Description Ref Default :OUTPut :GAIN :OFFSet [:STATe] :RELative OUTPut Subsystem: Specify gain factor (M); 1e-9 to 1e6. Specify offset (B); –1.2 to 1.2. Enable or disable Analog Output.
Remote Operation 11 Remote Operation
11-2 Remote Operation • • • Selecting and configuring an interface — Explains how to select and configure an interface: GPIB or RS-232.
Remote Operation 11-3 Selecting and configuring an interface Interfaces The Model 2182 Nanovoltmeter supports two built-in remote interfaces: • • GPIB Interface RS-232 Interface You can use only one interface at a time. At the factory, the GPIB bus is selected. You can select the interface only from the front panel. The interface selection is stored in non-volatile memory; it does not change when power has been off or after a remote interface reset. GPIB interface — The GPIB is the IEEE-488 interface.
11-4 Remote Operation Interface selection and configuration procedures When you select (enable) the GPIB interface, the RS-232 interface disables. Conversely, selecting (enabling) the RS-232 interface disables the GPIB interface. GPIB interface The GPIB interface is selected and configured from the GPIB menu structure.
Remote Operation 11-5 Perform the following steps to select and configure the RS-232 interface: NOTE 1. 2. 3. 4. 5. NOTE To retain a present RS-232 setting, press ENTER with the setting displayed. You can exit from the menu structure at any time by pressing EXIT. Press SHIFT and then RS232 to access the RS-232 menu. The present state (on or off) of the RS-232 is displayed. To enable the RS-232 interface: A. Place the cursor on the on/off selection by pressing the key. B.
11-6 Remote Operation GPIB operation and reference GPIB bus standards The GPIB bus is the IEEE-488 instrumentation data bus with hardware and programming standards originally adopted by the IEEE (Institute of Electrical and Electronic Engineers) in 1975. The Model 2182 conforms to these standards: • • IEEE-488-1987.1 IEEE-488-1987.
Remote Operation 11-7 Figure 11-2 IEEE-488 connections Instrument Instrument Instrument Controller To avoid possible mechanical damage, stack no more than three connectors on any one unit. NOTE To minimize interference caused by electromagnetic radiation, use only shielded IEEE-488 cables. Available shielded cables from Keithley are Models 7007-1 and 7007-2. To connect the Model 2182 to the IEEE-488 bus, follow these steps: 1.
11-8 Remote Operation 2. 3. 4. NOTE Tighten the screws securely, making sure not to over tighten them. Connect any additional connectors from other instruments as required for your application. Make sure that the other end of the cable is properly connected to the controller. Most controllers are equipped with an IEEE-488 style connector, but a few may require a different type of connecting cable. See your controllers instruction manual for information about properly connecting to the IEEE-488 bus.
Remote Operation 11-9 Then initialize the interface card as address 21: CALL INITIALIZE (21, 0) Initialize also sends out an interface clear (IFC) to the entire GPIB system to initialize the other devices (see “General bus commands, IFC (interface clear)”). A typical program fragment includes a CALL SEND command and a CALL ENTER command. The CALL SEND command sends a program message (command string) to the Model 2182.
11-10 Remote Operation Transmit — A transmit routine is used to send General Bus Commands. It contains a series of GPIB commands to be carried out. In addition to the commands listed in Table 11-1, there are other commands used in the transmit command string. Some of the more frequently used ones are explained as follows (refer to the User’s Manual for the interface card for details on all the commands): UNL UNT LISTEN 7 MTA Unlisten — Disables any listeners that may exist.
Remote Operation 11-11 Program Fragment CALL TRANSMIT (“UNL LISTEN 7 LLO”, status%)‘ Lock out front panel. CALL TRANSMIT (“UNL LISTEN 7 GTL”, status%)‘ Lock out front panel. GTL (go to local) Use the GTL command to put a remote mode instrument into local mode. The GTL command also restores front panel key operation. Program Fragment CALL TRANSMIT (“MTA LISTEN 7 REN”, status%)‘ Place 2182 in remote.
11-12 Remote Operation SPE, SPD (serial polling) Use the serial polling sequence to obtain the Model 2182 serial poll byte. The serial poll byte contains important information about internal functions. Generally, the serial polling sequence is used by the controller to determine which of several instruments has requested service with the SRQ line. However, the serial polling sequence may be performed at any time to obtain the status byte from the Model 2182.
Remote Operation 11-13 LOCAL key The LOCAL key cancels the remote state and restores local operation of the instrument. Pressing the LOCAL key also turns off the REM indicator and returns the display to normal if a user-defined message was displayed. If the LLO (Local Lockout) command is in effect, the LOCAL key is also inoperative. Status structure See Figure 11-4 for the Model 2182’s status structure. Instrument events, such as errors, are monitored and manipulated by four status register sets.
11-14 Remote Operation Figure 11-4 Model 2182 status model structure Questionable Event Enable Register Questionable Questionable Condition Event Register Register Temperature Summary Calibration Summary ACAL Summary (Always Zero) 0 1 2 3 Temp 5 6 7 Cal Acal 10 11 12 13 14 15 0 1 2 3 Temp 5 6 7 Cal Acal 10 11 12 13 14 15 & & & & & & & & & & & & & & & & 0 1 2 3 Temp 5 6 7 Cal Acal 10 11 12 13 14 15 Logical OR Error Queue Output Queue Standard Event Status Enable Register Standard Event Status
Remote Operation 11-15 Condition registers As Figure 11-4 shows, some register sets have a condition register. A condition register is a real-time, read-only register that constantly updates to reflect the present operating conditions of the instrument. For example, while a measurement is being performed, bit B4 (Meas) of the Operation Condition Register is set. When the measurement is completed, bit B4 clears. Use the :CONDition? query commands in the STATus Subsystem to read the condition registers.
11-16 Remote Operation Figure 11-5 Standard event status * ESR ? PON URQ CME EXE DDE QYE OPC Standard Event (B15 - B8) (B7) (B6) (B5) (B4) (B3) (B2) (B1) (B0) Status Register & & & & OR & To Event Summary Bit (ESB) of Status Byte Register (See Figure 11-9).
Remote Operation 11-17 Figure 11-7 Measurement event status BFL BHF BAV RAV HL2 LL2 HL1 LL1 ROF Measurement (B15 - B10) (B9) (B8) (B7) (B6) (B5) (B4) (B3) (B2) (B1) (B0) Condition Register BFL BHF BAV RAV HL2 LL2 HL1 LL1 ROF Measurement Event (B15 - B10) (B9) (B8) (B7) (B6) (B5) (B4) (B3) (B2) (B1) (B0) Register & & & OR & & & & To Measurement Summary Bit (MSB) of Status Byte Register.
11-18 Remote Operation Queues The Model 2182 uses two queues, which are first-in, first-out (FIFO) registers: • • Output Queue – Used to hold reading and response messages. Error Queue – Used to hold error and status messages. The Model 2182 status model (Figure 11-4) shows how the two queues are structured with the other registers. Output queue The output queue holds data that pertains to the normal operation of the instrument.
Remote Operation 11-19 Status byte and service request (SRQ) Service request is controlled by two 8-bit registers: the Status Byte Register and the Service Request Enable Register. Figure 11-9 shows the structure of these registers.
11-20 Remote Operation The IEEE-488.2 standard uses the *STB? common query command to read the Status Byte Register. When reading the Status Byte Register using the *STB? command, bit B6 is called the MSS bit. None of the bits in the Status Byte Register are cleared when using the *STB? command to read it. The IEEE-488.1 standard has a serial poll sequence that also reads the Status Byte Register and is better suited to detect a service request (SRQ).
Remote Operation 11-21 The serial poll automatically resets RQS of the Status Byte Register. This allows subsequent serial polls to monitor bit B6 for an SRQ occurrence generated by other event types. After a serial poll, the same event can cause another SRQ, even if the event register that caused the first SRQ has not been cleared. A serial poll clears RQS but does not clear MSS. The MSS bit stays set until all Status Byte event summary bits are cleared.
11-22 Remote Operation • Parameter types – The following are some of the common parameter types: Boolean – Used to enable or disable an instrument operation. 0 or OFF disables the operation, and 1 or ON enables the operation. :OUTPut:RELative ON Enable Analog Output Rel Name Parameter – Select a parameter name from a listed group. = NEVer = NEXT :CALCulate:FORMat MXB Numeric Representation Format – A number that can be expressed as an integer (e.g., 8) a real number (e.g.
Remote Operation 11-23 Query commands The Query command requests the presently programmed status. It is identified by the question mark (?) at the end of the fundamental form of the command. Most commands have a query form. :TRIGger:TIMer?Queries the timer interval Most commands that require a numeric parameter() can also use the DEFault, MINimum, and MAXimum parameters for the query form.
11-24 Remote Operation Short-form rules Use the following rules to determine the short-form version of any SCPI command: • If the length of the command word is four letters or less, no short form version exists. :auto = :auto These rules apply to command words that exceed four letters: • If the fourth letter of the command word is a vowel, delete it and all the letters after it.
Remote Operation 11-25 Single command messages The above command structure has three levels. The first level is made up of the root command (:STATus) and serves as a path. The second level is made up of another path (:OPERation) and a command (:PRESet). The third path is made up of one command for the :OPERation path.
11-26 Remote Operation Using common commands and SCPI commands in the same message Both common commands and SCPI commands can be used in the same message as long as they are separated by semicolons (;). A common command can be executed at any command level and will not affect the path pointer. :stat:oper:enab ; *ESE Program message terminator (PMT) Each program message must be terminated with an LF (line feed), EOI (end or identify), or an LF+EOI.
Remote Operation 11-27 Message exchange protocol Two rules summarize the message exchange protocol: Rule 1. Always tell the Model 2182 what to send to the computer. The following two steps must always be performed to send information from the instrument to the computer: 1. 2. Send the appropriate query command(s) in a program message. Address the Model 2182 to talk. Rule 2. The complete response message must be received by the computer before another program message can be sent to the Model 2182.
11-28 Remote Operation Flow control (signal handshaking) Signal handshaking between the controller and the instrument allows the two devices to communicate to each other regarding being ready or not ready to receive data. The Model 2182 does not support hardware handshaking (flow control). Software flow control is in the form of X__ON and X__OFF characters and is enabled when XonXoFF is selected from the RS232 FLOW menu.
Remote Operation 11-29 RS-232 connections The RS-232 serial port can be connected to the serial port of a controller (i.e., personal computer) using a straight through RS-232 cable terminated with DB-9 connectors. Do not use a null modem cable. The serial port uses the transmit (TXD), receive (RXD), and signal ground (GND) lines of the RS-232 standard. It does not use the hardware handshaking lines, CTS and RTS.
11-30 Remote Operation Table 11-3 PC serial port pinout Signal DB-9 Pin Number DB-25 Pin Number DCD, data carrier detect RXD, receive data TXD, transmit data DTR, data terminal ready GND, signal ground DSR, data set ready RTS, request to send CTS, clear to send RI, ring indicator 1 2 3 4 5 6 7 8 9 8 3 2 20 7 6 4 5 22 Error messages See Appendix B for RS-232 error messages.
Common Commands 12 Common Commands
12-2 Common Commands Common commands (summarized in Table 12-1) are device commands that are common to all devices on the bus. These commands are designated and defined by the IEEE-488.2 standard. Table 12-1 IEEE-488.
Common Commands *CLS — Clear Status 12-3 Clear status registers and error queue Description Use the *CLS command to clear (reset to 0) the bits of the following registers in the Model 2182: • • • • • Standard Event Register Operation Event Register Error Queue Measurement Event Register Questionable Event Register This command also forces the instrument into the operation complete command idle state and operation complete query idle state.
12-4 Common Commands *ESE – Event Enable *ESE? – Event Enable Query Program the standard event enable register Read the standard event register Parameters = 0 1 4 8 16 32 64 128 255 Clear register Set OPC (B0) Set QYE (B2) Set DDE (B3) Set EXE (B4) Set CME (B5) Set URQ (B6) Set PON (B7) Set all bits Description Use the *ESE command to program the Standard Event Enable Register.
Common Commands 12-5 If a command error (CME) occurs, bit B5 of the Standard Event Status Register sets. If a query error (QYE) occurs, bit B2 of the Standard Event Status Register sets. Since both of these events are unmasked (enabled), the occurrence of any of them causes the ESB bit in the Status Byte Register to set. Read the Standard Event Status Register using the *ESE? query command.
12-6 Common Commands *ESR? – Event Status Register Query Read register and clear it Description Use this command to acquire the value (in decimal) of the Standard Event Register (see Figure 12-2). The binary equivalent of the returned decimal value determines which bits in the register are set. The register is cleared on power-up or when *CLS is sent. A set bit in this register indicates that a particular event has occurred.
Common Commands • • 12-7 Bit B6, User Request (URQ) – A set bit indicates that the LOCAL key on the Model 2182 front panel was pressed. Bit B7, Power ON (PON) – A set bit indicates that the Model 2182 has been turned off and turned back on since the last time this register has been read.
12-8 Common Commands *OPC – Operation Complete Set the OPC bit in the standard event register after all pending commands are complete Description After the *OPC command is sent, the Operation Complete bit (bit B0) of the Standard Event Status Register will set immediately after the last pending command is completed.
Common Commands 12-9 Program example The first group of commands send the *OPC command after the :INITiate command and verifies that the OPC bit in the Standard Event Status Register does not set while the instrument continues to make measurements (not in idle). The second group of commands returns the Model 2182 to the idle state and verifies that the OPC bit did set. SYST : PRES INIT : CONT OFF ABORt INIT : IMM *OPC *ESR? ‘ ‘ ‘ ‘ ‘ ‘ Return 2182 to default setup. Disables continuous initiation.
12-10 Common Commands *OPC? – Operation Complete Query Place a “1” in the output queue after all pending operations are completed Description When this common command is sent, an ASCII “1” will be placed in the Output Queue after the last pending operation is completed. When the Model 2182 is then addressed to talk, the “1” in the Output Queue will be sent to the computer. The “1” in the Output Queue will set the MAV (Message Available) bit (B4) of the Status Byte Register.
Common Commands NOTE 12-11 The following commands take a long time to process and may benefit from using *OPC or OPC?: *RST and SYST:PRES *RCL and *SAV CALC2:IMM and CALC2:IMM? – Only when performing the standard deviation calculation on a large buffer. RS-232 operation can also benefit from *OPC?. Comments: 1. Resets the Model 2182 to default operating conditions. 2. Disables continuous initiation and aborts operation. Places 2182 in the idle state. 3.
12-12 Common Commands *RST – Reset Return 2182 to *RST defaults Description When the *RST command is sent, the Model 2182 performs the following operations: 1. 2. 3. Returns the Model 2182 to the *RST default conditions (see SCPI tables). Cancels all pending commands. Cancels response to any previously received *OPC and *OPC? commands. NOTE: For RS-232 operation (and in some cases, GPIB operation), *OPC or *OPC? should be used with *RST, which is a slow responding command.
Common Commands 12-13 Description Use the *SRE command to program the Service Request Enable Register. Send this command with the decimal equivalent of the binary value that determines the desired state (0 or 1) of each bit in the register. This register is cleared on power-up. This enable register is used along with the Status Byte Register to generate service requests (SRQ).
12-14 Common Commands *STB? – Status Byte Query Read status byte register Description Use the *STB? query command to acquire the value (in decimal) of the Status Byte Register. The Status Byte Register is shown in Figure 12-4. The binary equivalent of the decimal value determines which bits in the register are set. All bits, except Bit B6, in this register are set by other event registers and queues. Bit 6 sets when one or more enabled conditions occur.
Common Commands 12-15 Figure 12-4 Status byte register Bit Position B7 B6 B5 B4 B3 B2 B1 MSS, ESB MAV QSB EAV RQS B0 Event OSB Decimal Weighting 128 64 32 16 8 4 1 (27 ) (26 ) (25 ) (24 ) (23 ) (22 ) (20 ) Value 0/1 0/1 0/1 0/1 0/1 0/1 0/1 Value : 1 = Event Bit Set 0 = Event Bit Cleared *TRG – Trigger MSB Events : OSB = Operation Summary Bit MSS = Master Summary Status RQS = Request Service ESB = Event Summary Bit MAV = Message Available QSB = Questionable Summary Bit
12-16 Common Commands *WAI – Wait-to-Continue Prevent execution of commands until previous commands are completed Description Two types of device commands exist: • Sequential commands – A command whose operations are allowed to finish before the next command is executed. Overlapped commands – A command that allows the execution of subsequent commands while device operations of the Overlapped command are still in progress.
SCPI Signal Oriented Measurement Commands 13 SCPI Signal Oriented Measurement Commands
13-2 SCPI Signal Oriented Measurement Commands The signal oriented measurement commands are used to acquire readings. You can use these high level instructions to control the measurement process. These commands are summarized in Table 13-1. Table 13-1 Signal oriented measurement command summary Command Description CONFigure: Places the Model 2182 in a “one-shot” measurement mode for the specified function. :FETCh? Requests the latest reading.
SCPI Signal Oriented Measurement Commands • • • 13-3 Buffer operation is disabled. A storage operation presently in process will be aborted. Autozero is set to the *RST default value. All operations associated with stepping or scanning are disabled. This command is automatically asserted when the :MEASure? command is sent. Program fragment CALL SEND (7, “:conf:volt”, status%) CALL SEND (7, “:trig:del 0.
13-4 SCPI Signal Oriented Measurement Commands If the instrument is in the idle state, :INITiate takes the instrument out of the idle state. If continuous initiation is enabled, (:INITiate:CONTinuous ON), then the :INITiate command generates an error and ignores the command. NOTE You cannot use the :READ? command if sample count >1 (see Trigger subsystem) and there are readings stored in the buffer (error -225, out of memory). Either set sample count to one or clear the buffer.
SCPI Reference Tables 14 SCPI Reference Tables
14-2 SCPI Reference Tables • • • • • • • • • • • • Table 14-1 — CALCulate command summary Table 14-2 — CALibrate command summary Table 14-3 — DISPlay command summary Table 14-4— FORMat command summary Table 14-5 — OUTPut command summary Table 14-6 — ROUTe command summary Table 14-7 — SENSe command summary Table 14-8 — STATus command summary Table 14-9 — SYSTem command summary Table 14-10 — TRACe command summary Table 14-11 — Trigger command summary Table 14-12— UNIT command summary General notes • • •
SCPI Reference Tables 14-3 Table 14-1 CALCulate command summary Command Description :CALCulate[1] :FORMat :FORMat? :KMATh :MMFactor :MMFactor? :MBFactor :MBFactor? :MUNits Path to configure and control KMATh calculations. Select math format; NONE, MXB or PERCent. Query math format. Configure math calculations: Set “m” for mX+b calculation; -100e6 to 100e6. Query “m” factor. Set “b” for mX+b calculation; -100e6 to 100e6. Query “b” factor.
14-4 SCPI Reference Tables Table 14-1 CALCulate command summary (cont.) Command [:IMMediate] :AUTO :AUTO? :LIMit2 :UPPer [:DATA] [:DATA]? :LOWer [:DATA] [:DATA]? :STATe :STATe? :FAIL? :CLEar [:IMMediate] :AUTO :AUTO? :IMMediate Description Clear limit test results. Enable or disable clearing of limit test results when a new trigger model cycle starts. Query state of auto clear. Limit 2 Testing: Configure upper limit: Specify limit; -100e6 to 100e6. Query upper limit.
SCPI Reference Tables 14-5 Table 14-3 DISPlay command summary Command :DISPlay :ENABle :ENABle? [:WINDow[1]] :TEXT :DATA :DATA? :STATe :STATe? Description Default Parameter Ref SCPI Sec 15 Turn front panel display on or off. Query display state. Path to control user test messages: √ √ √ √ √ √ √ √ (Note 1) (Note 2) Define ASCII message “a” (up to 12 characters). Read text message. Enable or disable text message mode. Query state of text message mode. (Note 3) Notes: 1.
14-6 SCPI Reference Tables Table 14-5 OUTPut command summary Command :OUTPut :GAIN :GAIN? :OFFSet :OFFSet? [:STATe] [:STATe]? :RELative :RELative? Description Default Parameter Ref SCPI Sec 10 Set analog output gain (M); -100e6 to 100e6 Query analog output gain. Set analog output offset (B); -1.2 to 1.2. Query analog output offset. Enable or disable analog output (OFF forces 0V). Query state of analog output. ON uses the present analog output voltage as the Rel value.
SCPI Reference Tables 14-7 Table 14-7 SENSe command summary Command :SENSe[1] :FUNCtion :FUNCtion? :DATA [:LATest]? :FRESh? :CHANnel :CHANnel? :HOLD :WINDow :WINDow? :COUNt :COUNt? :STATe :STATe? :VOLTage[:DC] :NPLCycles :NPLCycles? :APERture :APERture? :DIGits :DIGits? :RATio :RATio? :DELTa :DELTa? [:CHANnel1] :RANGe [:UPPer] [:UPPer]? :AUTO :AUTO? :REFerence :STATe :STATe? :ACQuire Description Select function; ‘VOLTage[:DC]’ or ‘TEMPerature’.
14-8 SCPI Reference Tables Table 14-7 SENSe command summary (cont.) Command :REFerence? :LPASs [:STATe] [:STATe]? :DFILter :WINDow :WINDow? :COUNt :COUNt? :TCONtrol :TCONtrol? [:STATe] [:STATe]? :CHANnel2 :LQMode :LQMode? :RANGe [:UPPer] [:UPPer]? :AUTO :AUTO? :REFerence :STATe :STATe? :ACQuire :REFerence? :LPASs [:STATe] [:STATe]? :DFILter :WINDow :WINDow? :COUNt :COUNt? :TCONtrol :TCONtrol? [:STATe] [:STATe]? Description Query Rel value.
SCPI Reference Tables 14-9 Table 14-7 SENSe command summary (cont.) Command :TEMPerature :TRANsducer :TRANsducer? :TCouple [:TYPE] [:TYPE]? :RJUNction :RSELect :RSELect? :SIMulated :SIMulated? :RTEMperature? :NPLCycles Description Path to configure temperature: Specify transducer; TCouple or INTernal. Query transducer. Thermocouple (TC): Set TC type; J, K, T, E, R, S, B or N. Query TC type. Reference junction: Set reference type; SIMulated or INTernal. Query reference type.
14-10 SCPI Reference Tables Table 14-7 SENSe command summary (cont.) Command :CHANnel2 :REFerence :STATe :STATe? :ACQuire :REFerence? :LPASs [:STATe] [:STATe]? :DFILter :WINDow :WINDow? :COUNt :COUNt? :TCONtrol :TCONtrol? [:STATe] [:STATe]? Description Channel 2 temperature commands: Specify reference (Rel) value for Channel 2; –328 to 3310. Enable or disable Rel. Query state of Rel. Use the voltage on Channel 2 as Rel. Query Rel value.
SCPI Reference Tables 14-11 Table 14-8 STATus command summary Command Description :STATus :MEASurement [:EVENt]? :ENABle :ENABle? :CONDition? :OPERation [:EVENt]? :ENABle :ENABle? :CONDition? :QUEStionable [:EVENt]? :ENABle :ENABle? :CONDition? :PRESet :QUEue [:NEXT]? :ENABle :ENABle? :DISable :DISable? :CLEar Measurement event registers: Read the event register. Program the enable register. Read the enable register. Read the condition register.
14-12 SCPI Reference Tables Table 14-9 SYSTem command summary Command :SYSTem :PRESet :FAZero [:STATe] [:STATe]? :AZERo [:STATe] [:STATe]? :LSYNc [:STATe] [:STATe]? :LFRequency? :POSetup :POSetup? :VERSion? :ERRor? :CLEar :KCLick :KCLick? :BEEPer [:STATe] [:STATe]? :KEY :KEY? Description Return to SYSTem:PRESet defaults. Path to control Front Autozero. Enable or disable Front Autozero. Query state of Front Autozero. Path to control Autozero: Enable or disable Autozero.
SCPI Reference Tables 14-13 Table 14-11 Trigger command summary Command Description :INITiate [:IMMediate] :CONTinuous :CONTinuous? :ABORt Path to Initiate measurement cycle(s): Initiate one cycle. Enable or disable continuous initiation. Query state of continuous initiation. Reset trigger system (goes to idle state). Default Parameter Ref SCPI Sec 7 :TRIGger Path to configure Trigger Layer: [:SEQuence[1]] :SOURce Select control source; IMMediate, TIMer, MANual, BUS, or EXTernal.
14-14 SCPI Reference Tables Table 14-12 UNIT command summary Command Description :UNIT :TEMPerature :TEMPerature? Select temperature units; C, F, or K. Query temperature units.
Additional SCPI Commands 15 Additional SCPI Commands
15-2 Additional SCPI Commands • • • • DISPlay subsystem — Covers the SCPI commands that are used to control the display. FORMat subsystem — Covers the SCPI commands to configure the format for readings that are sent over the bus. STATus subsystem — Covers the SCPI commands to configure and control the status registers. SYSTem subsystem — Covers miscellaneous SCPI commands.
Additional SCPI Commands 15-3 DISPlay subsystem The commands in this subsystem are used to control the display of the Model 2182 and are summarized in Table 14-3. :ENABle :DISPlay:ENABle Control display circuitry Parameters = 0 or OFF 1 or ON Disable display circuitry Enable display circuitry Description This command is used to enable and disable the front panel display circuitry. When disabled, the instrument operates at a higher speed. While disabled, the display is frozen.
15-4 Additional SCPI Commands FORMat subsystem The commands in this subsystem are used to select the data format for transferring instrument readings over the bus. The BORDer command and DATA command only affect readings transferred from the buffer (i.e., SENSE:DATA? or CALC:DATA? are always sent in ASCII). These commands are summarized in Table 14-4.
Additional SCPI Commands 15-5 SREal will select the binary IEEE754 single precision data format. Figure 15-2 shows the normal byte order format for each data element. For example, if three valid elements are specified, the data string for each reading conversion is made up of three 32-bit data blocks. Note that the data string for each reading conversion is preceded by a 2-byte header that is the binary equivalent of an ASCII # sign and 0.
15-6 Additional SCPI Commands :BORDer command :BORDer :FORMat:BORDer Specify binary byte order Parameters = NORMal Normal byte order for binary formats SWAPped Reverse byte order for binary formats Description This command is used to control the byte order for the IEEE754 binary formats. For normal byte order, the data format for each element is sent as follows: Byte 1 Byte 1 Byte 2 Byte 2 Byte 3 ...
Additional SCPI Commands 15-7 CHANnel: Corresponds the instrument reading to the channel number. Channel 0 corresponds to the sensor used to measure the internal temperature of the Model 2182. Channel 1 and Channel 2 corresponds to the two input channels of the instrument. For external scanning, the number corresponds to the channel number of the switching card. UNITs: This element attaches the function unit to the reading and the channel unit (internal or external) to the channel number.
15-8 Additional SCPI Commands Measurement Event Register: Bit B0, Reading Overflow (ROF) – Set bit indicates that the reading exceeds the measurement range of the instrument. Bit B1, Low Limit1 (LL1) – Set bit indicates that the reading is less than the Low Limit 1 setting. Bit B2, High Limit1 (HL1) – Set bit indicates that the reading is greater than the High Limit 1 setting. Bit B3, Low Limit 2 (LL2) – Set bit indicates that the reading is less than the Low Limit 2 setting.
Additional SCPI Commands 15-9 Questionable Event Register: Bits B0 through B3 – Not used. Bit B4, Temperature Summary (Temp) – Set bit indicates that an invalid reference junction measurement has occurred for thermocouple temperature measurements. Bits B5 through B7 – Not used. Bit B8, Calibration Summary (Cal) – Set bit indicates that an invalid calibration constant was detected during the power-up sequence. The instrument will instead use a default calibration constant.
15-10 Additional SCPI Commands Operation Event Register: Bit B0, Calibrating (Cal) – Set bit indicates that the instrument is calibrating. Bits B1 through B3 – Not used. Bit B4, Measuring (Meas) – Set bit indicates that the instrument is performing a measurement. Bit B5, Trigger Layer (Trig) – Set bit indicates that the instrument is waiting in the Trigger Layer of the Trigger Model. Bits B6 and B7 – Not used. Bit B8, Filter Settled (Filt) – Set bit indicates that the filter has settled.
Additional SCPI Commands 15-11 :ENABle command :ENABle :STATus:MEASurement:ENABle :STATus:QUEStionable:ENABle :STATus:OPERation:ENABle Program Measurement Event Enable Register Program Questionable Event Enable Register Program Operation Event Enable Register Parameters = 0 Clear register = 128 Set bit B7 1 Set bit B0 256 Set bit B8 2 Set bit B1 512 Set bit B9 4 Set bit B2 1024 Set bit B10 16 Set bit B4 16384 Set bit B14 32 Set bit B5 65535 Set al
15-12 Additional SCPI Commands Figure 15-7 Measurement event enable register Bit Position B15 - B10 B9 B8 B7 B6 B5 B4 B3 B2 B1 B0 Event BFL BHF BAV Decimal Weighting 512 256 128 32 16 8 4 2 1 (29 ) (28 ) (27 ) (25 ) (24 ) (23 ) (22 ) (21 ) (20 ) Value 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 0/1 Value : 1 = Measurement Event Set 0 = Measurement Event Cleared RAV HL2 LL2 HL1 LL1 ROF Events : BFL = Buffer Full BHF = Buffer Half Full BAV = Buffer Available RAV = Reading
Additional SCPI Commands 15-13 Figure 15-9 Operation event enable register Bit Position B15 - B11 B10 B9 B8 B7, B6 B5 B4 B3-B1 B0 Event Idle Filt Decimal Weighting 1024 256 (2 8 ) (2 5 ) (24 ) (20 ) Value 0/1 0/1 0/1 0/1 0/1 (210) Value : 1 = Enable Operation Event 0 = Disable (Mask) Operation Event Trig Meas 32 16 Cal 1 Events : Idle = Idle state of the 2182 Filt = Filter Settled Trig = Trigger Layer Meas = Measuring Cal = Calibrating :CONDition? command :CONDition? :STATu
15-14 Additional SCPI Commands :PRESet command :PRESet :STATus:PRESet Return registers to default conditions Description When this command is sent, all bits of the following registers are cleared to zero (0): • • • Questionable Event Enable Register Measurement Event Enable Register Operation Event Enable Register NOTE Registers not included in the above list are not affected by this command.
Additional SCPI Commands 15-15 :ENABle :STATus:QUEue:ENABle Enable messages for Error Queue Parameter = (numlist) where numlist is a specified list of messages that you wish to enable for the Error Queue. Description On power-up, all error messages are enabled and will go into the Error Queue as they occur. Status messages are not enabled and will not go into the queue. This command is used to specify which messages you want enabled.
15-16 Additional SCPI Commands :CLEar :STATus:QUEue:CLEar Clears all messages from Error Queue Description This command is used to clear the Error Queue of all messages. :SYSTem subsystem The SYSTem subsystem commands are summarized in Table 14-9. :PRESet command :PRESet :SYSTem:PRESet Return to :SYSTem:PRESet defaults Description This command returns the instrument to states optimized for front panel operation. :SYSTem:PRESet defaults are listed in the SCPI tables (Table 14-1 through Table 14-12).
Additional SCPI Commands 15-17 :AZERo[:STATe] :SYSTem:AZERo[:STATe] Control Autozero Parameters = 0 or OFF 1 or ON Disable Autozero Enable Autozero Description With autozero disabled, measurement speed is increased. However, the zero and gain reference points will eventually drift resulting in inaccurate readings of the input signal. It is recommended that autozero only be disabled for short periods of time.
15-18 Additional SCPI Commands :BEEPer command :STATe :SYSTem:BEEPer:STATe Enable or disable beeper Parameters = 1 or ON 0 or OFF Enable beeper Disable beeper Description This command is used to enable or disable the beeper for limit tests and HOLD. :KCLick command :KCLick :SYSTem:KCLick Enable or disable keyclick Parameters = 1 or ON 0 or OFF Enable keyclick Disable keyclick Description This command is used to enable or disable the keyclick.
Additional SCPI Commands 15-19 :VERSion? command :VERSion? :SYSTem:VERSion? Read SCPI version Description This query command is used to read the version of the SCPI standard being used by the Model 2182. Example code: 1991.0 The above response message indicates the version of the SCPI standard. :ERRor? command :ERRor? :SYSTem:ERRor? Read Error Queue Description As error and status messages occur, they are placed in the Error Queue. This query command is used to read those messages.
15-20 Additional SCPI Commands :KEY command :KEY :SYSTem:KEY Simulate key-press Parameters = 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 SHIFT key DCV1 key DCV2 key RATIO key ACAL key FILT key REL key TEMP1 key — — up arrow key AUTO key down arrow key ENTER key right arrow key TEMP2 key = 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 LOCAL key EX-TRIG key TRIG key STORE key RECALL key VALUE key ON/OFF key left arrow key — STEP key SCAN key SAVE RESTORE key DIGITS key RATE key E
Additional SCPI Commands Figure 15-10 Key-press codes 1 2 3 4 5 6 7 8 16 11 HI STEP SCAN CH1 REM TALK LSTN SRQ SHIFT TIMER HOLD TRIG FAST CH2 CH3 MED SLOW CH4 CH5 REL FILT CH6 CH7 AUTO CH8 ERR CH10 MATH REAR CH9 BUFFER ! 4W STAT HI LO CHANNEL 2 2182 NANOVOLTMETER SHIFT MX+B % V1-V2 LSYNC TYPE OUTPUT AOUT TCOUPL DCV1 DCV2 V1/V2 ACAL FILT REL TEMP 1 TEMP 2 RANGE TEST RANGE DELAY LOCAL HOLD EX TRIG TRIG POWER 17 CONFIG HALT STEP SCAN 26 18 BUFFER
15-22 Additional SCPI Commands
Specifications A Specifications
2182A Nanovoltmeter Specifications VOLTS SPECIFICATIONS (20% OVER RANGE) CONDITIONS: 1PLC with 10 reading digital filter or 5PLC with 2 reading digital filter. ACCURACY: ±(ppm of reading + ppm of range) (ppm = parts per million) (e.g., 10ppm = 0.001%) CHANNEL 1 RANGE 1 RESOLUTION INPUT RESISTANCE 24 Hour TCAL ±1°C 90 Day TCAL ±5°C 1 Year TCAL ±5°C 2 Year TCAL ±5°C TEMPERATURE COEFFICIENT 0°-18°C & 28°-50°C 10.000000 mV2,3,4 1 nV >10 GΩ 20 + 4 40 + 4 50 + 4 60 + 4 (1 + 0.5)/°C 100.
⌠ 2182A Nanovoltmeter Specifications Temperature (Thermocouples)12 (DISPLAYED IN °C, °F, OR K. ACCURACY BASED ON ITS-90, EXCLUSIVE OF THERMOCOUPLE ERRORS.) RESOLUTION ACCURACY 90 Day/1 Year 23° ±5°C Relative to Simulated Reference Junction TYPE RANGE J -200 to +760°C 0.001°C ±0.2°C K -200 to +1372°C 0.001°C ±0.2°C N -200 to +1300°C 0.001°C ±0.2°C T -200 to +400°C 0.001°C ±0.2°C E -200 to +1000°C 0.001°C ±0.2°C R 0 to +1768°C 0.1°C ±0.2°C S 0 to +1768°C 0.1°C ±0.
⌠ 2182A Nanovoltmeter Specifications GENERAL SPECIFICATIONS ANALOG OUTPUT POWER SUPPLY: 100V/120V/220V/240V. LINE FREQUENCY: 50Hz, 60Hz, and 400Hz, automatically sensed at power-up. POWER CONSUMPTION: 22VA MAXIMUM OUTPUT: ±1.2V. ACCURACY: ±(0.1% of output + 1mV). OUTPUT RESISTANCE: 1kΩ ±5%. GAIN: Adjustable from 10-9 to 106. With gain set to 1, a full range input will produce a 1V output. OUTPUT REL: Selects the value of input that represents 0V at output.
Status and Error Messages B Status and Error Messages
B-2 Status and Error Messages Table B-1 Status and error messages Number Description Event -440 -430 -420 -410 -363 -350 -330 -314 -315 -260 -241 -230 -225 -224 -223 -222 -221 -220 -215 -214 -213 -212 -211 -210 -202 -201 -200 -178 -171 -170 -168 -161 -160 -158 -154 -151 -150 Query unterminated after indefinite response Query deadlocked Query unterminated Query interrupted Input buffer overrun Queue overflow Self-test failed Save/recall memory lost Configuration memory lost Expression error Hardware mi
Status and Error Messages Table B-1 (cont.
B-4 Status and Error Messages Table B-1 (cont.
Status and Error Messages Table B-1 (cont.
B-6 Status and Error Messages
Measurement Considerations C Measurement Considerations
C-2 Measurement Considerations Measurement considerations Low-level voltage measurements made using the Model 2182 can be adversely affected by various types of noise or other unwanted signals that can make it very difficult to obtain accurate voltage readings. Some of the phenomena that can cause unwanted noise include thermoelectric effects (thermocouple action), source resistance noise, magnetic fields, and radio frequency interference.
Measurement Considerations C-3 Thermoelectric generation Figure C-1 shows a representation of how thermal EMFs are generated. The test leads are made of the A material, while the source under test is the B material. The temperatures between the junctions are shown as T1 and T2.
C-4 Measurement Considerations Minimizing thermal EMFs To minimize thermal EMFs, use only copper wires, lugs, and test leads for the entire test setup. Also, it is imperative that all connecting surfaces are kept clean and free of oxides. As noted in Table C-1, copper-to-copper oxide junctions can result in thermal EMFs as high as 1mV/°C. Even when low-thermal cables and connections are used, thermal EMFs can still be a problem in some cases.
Measurement Considerations C-5 Johnson noise equation The amount of noise present in a given resistance is defined by the Johnson noise equation as follows: E RMS = 4kTRF where: ERMS = rms value of the noise voltage k = Boltzmann's constant (1.38 × 10–23J/K) T = Temperature (K) R = Source resistance (ohms) F = Noise bandwidth (Hz) At a room temperature of 293K (20°C), the above equation simplifies to: E RMS = 1.
C-6 Measurement Considerations Magnetic fields When a conductor loop cuts through magnetic lines of force, a very small current is generated. This phenomenon will frequently cause unwanted signals to occur in the test leads of a test system. If the conductor has sufficient length or cross-sectional area, even weak magnetic fields such as those of the earth can create sufficient signals to affect low-level measurements.
Measurement Considerations C-7 instrument LO signal leads and then back through power line ground. This circulating current develops a small but undesirable voltage between the LO terminals of the two instruments. This voltage will be added to the source voltage, affecting the accuracy of the measurement.
C-8 Measurement Considerations Shielding Proper shielding of all signal paths and sources being measured is important to minimize noise pickup in virtually any low-level measurement situation. Otherwise, interference from such noise sources as line frequency and RF fields can seriously corrupt measurements, rendering experimental data virtually useless. In order to minimize noise, a closed metal shield surrounding the source may be necessary, as shown in the example of Figure C-4.
Measurement Considerations C-9 Meter loading Loading of the voltage source by the Model 2182 becomes a consideration for high source resistance values. As the source resistance increases, the error caused by meter loading increases. Figure C-5 shows the method used to determine the percent error due to meter loading. The voltage source, VS, has a source resistance, RS, while the input resistance of the Model 2182 is RI, and the voltage measured by the nanovoltmeter is VM.
C-10 Measurement Considerations
Model 182 Emulation Commands D Model 182 Emulation Commands
D-2 Model 182 Emulation Commands The Model 2182 can be configured to accept device-dependent commands of the Keithley Model 182 Sensitive Digital Voltmeter. The commands for controlling the Model 2182 with the 182 language are provided in Table D-1. For details on Model 182 operation, refer to the Model 182 Instruction Manual. Since the architecture of the Model 2182 differs from that of the Model 182, some commands are different and cannot be used.
Model 182 Emulation Commands D-3 Table D-1 Model 182 device-dependent command summary (cont’d) Mode Save/Recall Setup SRQ Mask Enable/Disable Filter Analog Filter Configuration Digital Filter Configuration Trigger Interval Range Integration Period Trigger Mode Command K2 K3 L0 L1 L2 M0 M1 M2 M4 M8 M16 M32 M128 N0 N1 O0 O1 P0 P1 P2 P3 Qvalue R0 R1 R2 R3 R4 R5 R6 R7 R8 S0 S1 S2 S3 T0 T1 T2 T3 Description Enable EOI, disable bus hold-off on X Disable EOI, disable bus hold-off on X Save current setup
D-4 Model 182 Emulation Commands Table D-1 Model 182 device-dependent command summary (cont’d) Mode Alternate Output Analog Output Trigger Delay Execute Terminators Reading Relative Command T4 T5 T6 T7 T8 T9 T10 U0 U1 U2 U3 U4 U5 U6 U7 U8 U9 U10 U12 U13 V0,gain W0 Wvalue X Y0 Y1 Y2 Y3 Y10 Y13 Z0 Z1 Z2,value Z3 Description Multiple on X One-shot on X Multiple on external One-shot on external Multiple on manual (TRIG key) or bus H0X One-shot on manual (TRIG key) or bus H0X Disable all triggers Send ma
Model 182 Emulation Commands D-5 NOTES: 1. “A” Commands — The maximum number of characters for the A1 command string is 12. The A2 and A3 commands are not supported. 2. “C” Commands — Calibration commands are not supported by the 182 language. You must use the SCPI language to calibrate the Model 2182 over the bus. 3. “G” Commands — The G4 through G7 commands are not supported by the 182 language. The Model 182 does not use time stamp. 4.
D-6 Model 182 Emulation Commands
Example Programs E Example Programs
E-2 Example Programs Program examples All examples presume QuickBASIC version 4.5 or higher and a CEC IEEE-488 interface card with CEC driver version 2.11 or higher, with the Model 2182 at address 7 on the IEEE-488 bus. Changing function and range The Model 2182 has independent range control for each of its two voltage measurement functions. This means, for example, that autorange can be turned on for DCV1 while leaving it off for DCV2. Another difference is in the parameter to the range command.
Example Programs 'Example program to demonstrate changing voltage function and range, 'taking readings on DCV1 and DCV2 'For QuickBASIC 4.5 and CEC PC488 interface card 'Edit the following line to where the QuickBASIC 'libraries are on your computer '$INCLUDE: 'c:\qb45\ieeeqb.
E-4 Example Programs One-shot triggering Other voltmeters generally have two types of triggering: one-shot and continuous. In oneshot, each activation of the selected trigger source causes one reading. In continuous, the voltmeter is idle until the trigger source is activated, at which time it begins taking readings at a specified rate.
Example Programs E-5 Generating SRQ on buffer full When your program must wait until the Model 2182 has completed an operation, it is more efficient to program the Model 2182 to assert the IEEE-488 SRQ line when it is finished, rather than repeatedly serial polling the instrument. An IEEE-488 controller will typically address the instrument to talk and then unaddress it each time it performs a serial poll. Repeated polling of the Model 2182 will generally reduce its overall reading throughput.
E-6 Example Programs Storing readings in buffer The reading buffer in the Model 2182 is flexible and capable. It has three controls, which are found in the TRACe subsystem. There are commands to control: • The size of the buffer (in readings). TRACe:POINts • Where the data is coming from (before or after the CALCulate1 math post-processing). TRACe:FEED SENSe1 store unprocessed readings TRACe:FEED CALCulate1 store math processed readings • Select buffer control mode.
Example Programs E-7 Taking readings using the :READ? command This programming example demonstrates a simple method for taking and displaying (on the computer CRT) a specified number of readings. The number of readings is specified by the :SAMPle:COUNt command. When :READ? is asserted, the specified number of readings is taken. After all the readings are taken, they are sent to the computer. Note that these readings are also stored in the buffer.
E-8 Example Programs Controlling the Model 2182 via the RS-232 COM2 port This example program illustrates the use of the Keithley Model 2182 interfaced to the RS-232 COM2 port. The Model 2182 is set up to take 100 readings at the fastest possible rate (2000 per second). The readings are taken, sent across the serial port, and displayed on the screen. ' Example program controlling the Model 2182 via the RS-232 COM2 port ' For QuickBASIC 4.
IEEE-488 Bus Overview F IEEE-488 Bus Overview
F-2 IEEE-488 Bus Overview Introduction The IEEE-488 bus is a communication system between two or more electronic devices. A device can be either an instrument or a computer. When a computer is used on the bus, it serves as a supervisor of the communication exchange between all the devices and is known as the controller. Supervision by the controller consists of determining which device will talk and which device will listen.
IEEE-488 Bus Overview F-3 Figure F-1 IEEE-488 bus configuration TO OTHER DEVICES DEVICE 1 ABLE TO TALK, LISTEN AND CONTROL (COMPUTER) DATA BUS DEVICE 2 ABLE TO TALK AND LISTEN 2182 DEVICE 3 ONLY ABLE TO LISTEN (PRINTER) DATA BYTE TRANSFER CONTROL GENERAL INTERFACE MANAGEMENT DEVICE 4 ONLY ABLE TO TALK DIO 1–8 DATA (8 LINES) DAV NRFD NDAC IFC ATN SRQ REN EOI HANDSHAKE BUS MANAGEMENT There are two categories of controllers: system controller and basic controller.
F-4 IEEE-488 Bus Overview A device is placed in the talk or listen state by sending an appropriate talk or listen command. These talk and listen commands are derived from an instrument’s primary address. The primary address may have any value between 0 and 31, and is generally set by rear panel DIP switches or programmed in from the front panel of the instrument. The actual listen address value sent out over the bus is obtained by ORing the primary address with $20.
IEEE-488 Bus Overview F-5 EOI (End or Identify) — The EOI line is used to mark the end of a multi-byte data transfer sequence. SRQ (Service Request) — The SRQ line is used by devices when they require service from the controller. Handshake lines The bus handshake lines operate in an interlocked sequence. This method ensures reliable data transmission regardless of the transfer rate. Generally, data transfer will occur at a rate determined by the slowest active device on the bus.
F-6 IEEE-488 Bus Overview Once all NDAC and NRFD are properly set, the source sets DAV low, indicating to accepting devices that the byte on the data lines is now valid. NRFD will then go low, and NDAC will go high once all devices have accepted the data. Each device will release NDAC at its own rate, but NDAC will not be released to go high until all devices have accepted the data byte. The previous sequence is used to transfer both data, talk and listen addresses, as well as multiline commands.
IEEE-488 Bus Overview F-7 Table F-1 IEEE-488 bus command summary Command type Command State of ATN line Comments Uniline REN (Remote Enable) EOI IFC (Interface Clear) ATN (Attention) SRQ X X X Low X Set up devices for remote operation. Marks end of transmission. Clears interface. Defines data bus contents. Controlled by external device. Multiline Universal LLO (Local Lockout) DCL (Device Clear) SPE (Serial Enable) SPD (Serial Poll Disable) Low Low Low Low Locks out local operation.
7 (B) ATN (Attention) — The controller sends ATN while transmitting addresses or multiline commands. ≅ DEL n o SECONDARY COMMAND GROUP (SDC) : { k } z j m y i l x h v w g t u r s q p 6 (B) X 1 1 1 7 (A) SRQ (Service Request) — SRQ is asserted by a device when it requires service from a controller.
IEEE-488 Bus Overview F-9 Addressed multiline commands Addressed commands are multiline commands that must be preceded by the device listen address before that instrument will respond to the command in question. Note that only the addressed device will respond to these commands. Both the commands and the address preceding it are sent with ATN true. SDC (Selective Device Clear) — The SDC command performs essentially the same function as the DCL command except that only the addressed device responds.
F-10 IEEE-488 Bus Overview Common commands Common commands are commands that are common to all devices on the bus. These commands are designated and defined by the IEEE-488.2 standard. Generally, these commands are sent as one or more ASCII characters that tell the device to perform a common operation, such as reset. The IEEE-488 bus treats these commands as data in that ATN is false when the commands are transmitted. SCPI commands SCPI commands are commands that are particular to each device on the bus.
IEEE-488 Bus Overview F-11 Typical command sequences For the various multiline commands, a specific bus sequence must take place to properly send the command. In particular, the correct listen address must be sent to the instrument before it will respond to addressed commands. Table F-3 lists a typical bus sequence for sending the addressed multiline commands. In this instance, the SDC command is being sent to the instrument.
F-12 IEEE-488 Bus Overview IEEE command groups Command groups supported by the Model 2182 are listed in Table F-5. Common commands and SCPI commands are not included in this list.
IEEE-488 Bus Overview F-13 Interface function codes The interface function codes, which are part of the IEEE-488 standards, define an instrument’s ability to support various interface functions and should not be confused with programming commands found elsewhere in this manual. The interface function codes for the Model 2182 are listed in Table F-6.
F-14 IEEE-488 Bus Overview PP (Parallel Poll Function) — The instrument does not have parallel polling capabilities (PP0). DC (Device Clear Function) — DC1 defines the ability of the instrument to be cleared (initialized). DT (Device Trigger Function) — DTI defines the ability of the Model 2182 to have readings triggered. C (Controller Function) — The instrument does not have controller capabilities (C0). TE (Extended Talker Function) — The instrument does not have extended talker capabilities (TE0).
IEEE-488 and SCPI Conformance Information G IEEE-488 and SCPI Conformance Information
G-2 IEEE-488 and SCPI Conformance Information Introduction The IEEE-488.2 standard requires specific information about how the Model 2182 implements the standard. Paragraph 4.9 of the IEEE-488.2 standard (Std 488.2-1987) lists the documentation requirements. Table G-1 provides a summary of the requirements and provides the information or references the manual for that information. Table G-2 lists the coupled commands used by the Model 2182. The Model 2182 complies with SCPI version 1991.0.
IEEE-488 and SCPI Conformance Information Table G-1 (cont.) IEEE-488 documentation requirements Requirements Description or reference (15) (16) (17) (18) (19) (20) (21) (22) Macro information. Response to *IDN (identification). Storage area for *PUD and *PUD? Resource description for *RDT and *RDT? Effects of *RST, *RCL and *SAV. *TST information. Status register structure. Sequential or overlapped commands. (23) Operation complete messages. Not applicable. See “Common Commands” in Section 12.
G-4 IEEE-488 and SCPI Conformance Information
Measurement Queries H Measurement Queries
H-2 Measurement Queries :FETCh? What it does This command will simply return the latest available reading from an instrument. Limitations If the instrument does not have a reading available (indicated by dashes in the display), sending this command will cause a –230, “Data corrupt or stale” error. This query will not cause the box to trigger a reading, nor will it “wait” for a result if a reading is in progress. It is possible to get the same reading over and over using this query.
Measurement Queries H-3 Limitations This command won’t work if the trigger source is set for BUS or EXTERNAL. This will cause a –214, “Trigger deadlock” error. Under this condition, one should use a “:FETCh?” query or a “:DATA:FRESh?” query (see page H-4). If the trigger model is continuously initiating (:INIT:CONT ON), sending this query may cause a –213, “Init ignored” error, but will still give a new reading.
H-4 Measurement Queries [:SENSe[1]]:DATA:FRESh? What it does This query is similar to the “:FETCh?” in that it returns the latest reading from the instrument, but has the advantage of making sure that it does not return the same reading twice. Limitations Like the “:FETCh?” query, this command does not trigger a reading. When appropriate This is a much better choice than the “:FETCh?” query because it can’t return the same reading twice.
Measurement Queries H-5 Examples One-shot reading, DC volts, no trigger, fastest rate *RST :INITiate:CONTinuous OFF;:ABORt :SENSe:FUNCtion ‘VOLTage:DC’ :SENSe:VOLTage:DC:RANGe 10 :SENSe:VOLTage:DC:NPLC 0.01 :DISPlay:ENABle OFF :SYSTem:AZERo:STATe OFF :SENSe:VOLTage:DC:LPASs OFF :SENSe:VOLTage:DC:DFILter OFF :TRIGger:COUNt 1 :READ? (Enter reading) // Use fixed range for fastest readings. // Use lowest NPLC setting for fastest readings. // Turn off display to increase speed.
H-6 Measurement Queries
Delta, Pulse Delta and Differential Conductance I Delta, Pulse Delta, and Differential Conductance
I-2 Delta, Pulse Delta, and Differential Conductance Overview NOTE With the use of a bi-polar current source, the Model 2182 can perform basic Delta measurements. See Section 5 of this manual for details on basic Delta measurements. This appendix summarizes the enhanced Delta, Pulse Delta, and Differential Conductance measurement processes that can be performed with the use of the Keithley Model 622x Current Source. It does NOT provide the procedures to configure and perform these measurements.
Delta, Pulse Delta, and Differential Conductance I-3 Operation overview The Model 6220 or 6221 Current Source can be used with a Model 2182/2182A Nanovoltmeter to perform Delta and Differential Conductance. The Model 2182A/6221 combination can also perform Pulse Delta. These operations use a delta current-reversal technique to cancel the effects of thermal EMFs.
I-4 Delta, Pulse Delta, and Differential Conductance Figure I-1 Delta, Pulse Delta, and Differential Conductance measurements A) Delta measurements 2182/2182A A/D 2182/2182A A/D 2182/2182A A/D I-High DELTA Reading 1st 622x 0 I-Source DELTA DELTA Reading 3rd Reading 2nd DELTA Reading 4th I-Low 2182/ 2182/ 2182A 2182A A/D A/D 1st Delta Cycle 2nd Delta Cycle 2182/ 2182A A/D 3rd Delta Cycle 4th Delta Cycle B) Pulse Delta measurements 2182A A/D 2182A A/D 2182A A/D I-High 6221 I-Source 2182A A/D
Delta, Pulse Delta, and Differential Conductance I-5 Test system configurations There are two test system configurations that can be used for Delta, Pulse Delta, and Differential Conductance measurements and are shown in Figure I-2. One is for front panel stand-alone operation and the other is for remote programming (PC control system). Both systems use serial communications (via RS-232 interface) between the Model 622x and the Model 2182/2182A.
I-6 Delta, Pulse Delta, and Differential Conductance Delta measurement process The Delta process is shown in Figure I-3. As shown, three Model 2182/2182A A/D conversions are performed to yield a single Delta reading. When Delta starts, three Model 2182/2182A A/Ds (A, B, and C) are performed and the Delta reading is calculated. After the 1st Delta cycle, the moving-average technique is then used. As shown, a Delta reading is yielded for every subsequent Model 2182/2182A A/D.
Delta, Pulse Delta, and Differential Conductance The following equation can be used to calculate any Delta reading: X – 2Y + Z n Delta = -------------------------- • ( – 1 ) 4 Where: X, Y, and Z are the three A/D measurements for a Delta reading. n = Delta Cycle Number – 1 Example – Calculate the 21st Delta reading: X, Y, and Z are the three A/D measurements for the 21st Delta reading.
I-8 Delta, Pulse Delta, and Differential Conductance Delta calculation example Assume you wish to measure the voltage across a 1Ω DUT using a constant +10mA current source and a voltmeter. Ideally, the measured voltage would be 10mV (V = I x R). However, due to a 10µV thermal EMF in the test leads, the voltmeter actually reads 10.01mV (0.1% error due to EMF). The error contributed by EMF can be eliminate by using Delta.
Delta, Pulse Delta, and Differential Conductance I-9 Pulse Delta process Pulse Delta measurements For Pulse Delta, the Model 6221 outputs current pulses. Current pulses that have a short pulse width are ideal to test a low-power DUT that is heat sensitive. By default, Pulse Delta uses a 3-point repeating-average algorithm to calculate readings. Each Pulse Delta reading is calculated using A/D measurements for a low pulse, a high pulse, and another low pulse.
I-10 Delta, Pulse Delta, and Differential Conductance Pulse Delta calculation example 3-point measurement technique – Assume you want to measure the voltage across a low power 1Ω DUT. The Pulse Delta process will reduce DUT heating and eliminate the effects of thermal EMFs. Assume the Model 6221 is configured to output +10mA and 0mA pulses. Due to a 10µV thermal EMF in the test leads, the following Model 2182A measurement conversions (A/Ds) are made for the first Pulse Delta cycle. A/D A = 0.
Delta, Pulse Delta, and Differential Conductance I-11 Measurement units The fundamental Pulse Delta measurement explained on the previous page is in volts. The reading can instead be converted into an Ohms (W), Siemens (S), or Power (W) reading by the Model 622x.
I-12 Delta, Pulse Delta, and Differential Conductance Figure I-5 Pulse timing One Pulse Delta Cycle 5, 6 (Interval = 5 PLC) Pulse Width 3 I-High 1 Pulse Width 3 I-Low 2 Low One Line Cycle 4 Pulse Width 3 High One Line Cycle 4 Low One Line Cycle 4 One Line Cycle 4 One Line Cycle 4 Power Line Voltage 1) 2) 3) 4) I-High can be set from -105mA to +105mA (default is 1mA). I-Low can be set from -105mA to +105mA (default is 0mA). Pulse Width can be set from 50µs to 12ms (default is 110µs).
Delta, Pulse Delta, and Differential Conductance I-13 Figure I-6 Pulse sweep output examples A) Staircase sweep pulse train: 2 to 10mA in 2mA steps Linear Scale Step = 2mA (set by the user) 10mA Stop 10mA 8mA Step 6mA Step 4mA Step 2mA Start 2mA Low 0mA LO HI Step LO LO One Pulse Delta Cycle (Sweep Delay) HI LO LO One Pulse Delta Cycle (Sweep Delay) HI LO LO One Pulse Delta Cycle (Sweep Delay) HI LO LO One Pulse Delta Cycle (Sweep Delay) HI LO One Pulse Delta Cycle (Sweep Del
I-14 Delta, Pulse Delta, and Differential Conductance Differential Conductance process Differential measurements can be used to study the individual slopes of an I-V (or V-I) curve. By applying a known differential current (dI) to a device, differential voltage (dV) measurements can be performed. With dI and dV known, differential conductance (dG) (and differential resistance dR) can be calculated. This differential measurement process is shown in Figure I-7.
Delta, Pulse Delta, and Differential Conductance Figure I-7 Differential Conductance measurement process 70µA 60µA Step Stop 50µA dV Calc #5 A/D Rdg G A/D Rdg = 2182/2182A voltage measurement conversion. dV Calc = Calculate differential voltage (dV) using last three A/D Rdgs.
I-16 Delta, Pulse Delta, and Differential Conductance Differential Conductance calculations dV calculations While the dV calculations for the first six dV readings are shown in Figure I-7, the following formula can be used to calculate any dV reading in the test: (X – Y) (Z – Y) ----------------- + ----------------2 2 n dV = ------------------------------------------ • ( – 1 ) 2 Where: X, Y, and Z are the three A/D measurements for a dV reading.
Delta, Pulse Delta, and Differential Conductance I-17 Measurement units The fundamental measurement for Differential Conductance is differential voltage (dV). However, the dV reading can be converted into a differential conductance (dG), differential resistance (dR), or power (Watts) reading by the Model 622x.
I-18 Delta, Pulse Delta, and Differential Conductance Power calculation With WATTS (power) measurement units selected, power for Differential Conductance is calculated using Average Voltage (see “Average Voltage calculation”) and Average Current.
Index C Cables, connectors, and adapters 1-4 CALCulate command summary 14-3 Calibrating resistor network dividers 5-18 CALibration command summary (user accessible) 14-4 Carrying case 1-5 Changing function and range E-2 Cleaning input connectors 1-13 Cleaning test circuit connectors 2-17 Command codes F-10 Common Commands 12-1 Common commands F-10 Configure and control analog output 10-5 Connection techniques 2-12 Connections 2-12 Contact information 1-3 Control source and event detection 7-4 Controlling t
E J Enabling limits 8-4 Example Programs E-1 External Stepping/Scanning 9-3 External trigger 7-8 External triggering 7-7 External triggering example 7-9 External triggering with BNC connections 7-12 Josephson Junction Arra 2-27 L Languages 11-3 Limit operations 8-3 Limits 8-1 Line power connection 1-14 Log sweep 5-24 Low power switches 2-24 Low-level considerations 2-22 Low-resistance measurement 2-23 LSYNC (line cycle synchronization) 2-8 F Filter 3-8 Filter considerations 5-15 Filter, Rel and Ranging
P SCPI programming - ratio and delta 5-16 SCPI programming - relative 4-4 SCPI programming - stepping and scanning 9-12 SCPI programming - triggering 7-13 SCPI programming - voltage and temperature measurements 2-20 SCPI Reference Tables 14-1 SCPI Signal Oriented Measurement Commands 13-1 Selecting and configuring an interface 11-3 Selecting Delta 5-9 Sending and receiving data 11-27 SENSe command summary 14-7 Setting limit values 8-4 Setting line voltage and replacing fuse 1-15 Shielding C-8 Sorting resis
Trigger model (remote operation) 7-13 Trigger model operation 7-15 trigger synchronization 5-14 Triggering 7-1 Triggering commands 7-16 Typical command sequences F-11 U Unaddress commands F-9 UNIT command summary 14-14 V Voltage and temperature connections 2-16 Voltage and Temperature Measurements 2-1 Voltage measurements 2-3 Voltage only connections 2-14 Voltmeter complete 7-8 W Warm-up 2-5 Warranty information 1-3
Service Form Model No. _______________ Serial No. __________________ Date _________________ Name and Telephone No. ____________________________________________________ Company _______________________________________________________________________ List all control settings, describe problem and check boxes that apply to problem.
Specifications are subject to change without notice. All Keithley trademarks and trade names are the property of Keithley Instruments, Inc. All other trademarks and trade names are the property of their respective companies. A G R EAT E R M EAS U R E O F C O N F I D E N C E Keithley Instruments, Inc. Corporate Headquarters • 28775 Aurora Road • Cleveland, Ohio 44139 • 440-248-0400 • Fax: 440-248-6168 • 1-888-KEITHLEY (534-8453) • www.keithley.
