DAQ BNC-2140 User Manual Dynamic Signal Acquisition Signal Conditioning Accessory BNC-2140 User Manual April 1998 Edition Part Number 321933A-01
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Important Information Warranty The BNC-2140 is warranted against defects in materials and workmanship for a period of one year from the date of shipment, as evidenced by receipts or other documentation. National Instruments will, at its option, repair or replace equipment that proves to be defective during the warranty period. This warranty includes parts and labor.
Contents About This Manual Organization of This Manual .........................................................................................vii Conventions Used in This Manual.................................................................................viii Related Documentation..................................................................................................viii Customer Communication .............................................................................................
Contents Glossary Index Figures Figure 2-1. Switch Settings and Signal Connections............................................... 2-2 Figure 3-1. BNC-2140 External 68-Pin Analog Connector .................................... 3-3 Figure 4-1. BNC-2140 Block Diagram ................................................................... 4-2 Tables Table 3-1. Table 3-2. BNC-2140 User Manual BNC Analog I/O Connector Signal Descriptions ..................................
About This Manual This manual describes the electrical and mechanical aspects of the BNC-2140 accessory and contains information concerning its operation. Organization of This Manual The BNC-2140 User Manual is organized as follows: • Chapter 1, Introduction, describes the BNC-2140 accessory, lists what you need to get started, explains how to unpack your BNC-2140, and describes optional equipment.
About This Manual Conventions Used in This Manual The following conventions are used in this manual: <> Angle brackets containing numbers separated by an ellipsis represent a range of values associated with a bit or signal name—for example, DIO<3..0>. This icon to the left of bold italicized text denotes a note, which alerts you to important information.
1 Introduction This chapter describes the BNC-2140 accessory, lists what you need to get started, explains how to unpack your BNC-2140, and describes optional equipment. Thank you for buying the BNC-2140 accessory for DSA.The BNC-2140 is a signal conditioning accessory specifically designed for use with a dynamic signal acquisition (DSA) series device.
Chapter 1 Introduction What You Need to Get Started To set up and use your BNC-2140 device, you will need the following: ❑ BNC-2140 ❑ One of the following DSA devices: PCI-4451 PCI-4452 NI 4551 NI 4552 ❑ BNC-2140 User Manual ❑ Your computer ❑ SHC68-C68-A1 analog cable Unpacking Your BNC-2140 is shipped in an antistatic plastic package to prevent electrostatic damage to the device. Several components on the device can be damaged by electrostatic discharge.
Chapter 1 Introduction If your application requires that you use a prepolarized microphone with a microphone preamplifier, contact Brüel and Kjær. Custom Cabling National Instruments offers cables of different lengths for the BNC-2140 accessory to connect your analog I/O signals to the DSA devices. National Instruments recommends that you not develop your own cabling solution due to the high-density connector that is required and the necessity to maintain high signal integrity.
Installation and Configuration 2 This chapter explains how to install and configure your BNC-2140 accessory. Installation Note You must turn the power off to your computer before installing the BNC-2140. The following are general installation instructions. 1. Insert either end of your SHC68-C68-A1 analog cable into the 68-pin connector on the BNC-2140. Insert the other end into the 68-pin connector on the DSA plug-in device. 2. Tighten the jack screws finger-tight on both ends of the cable. 3.
Chapter 2 Installation and Configuration ® Figure 2-1.
3 Signal Connections This chapter describes how to connect input and output signals to your BNC-2140. You can connect the external analog signals through six BNC connectors. Four BNC connectors are for input signals and two connectors are for output signals. The SHC68-C68-A1 shielded cable connects the BNC-2140 internal analog signal connector to the DSA plug-in device. A single 68-pin 0.8 mm VHDCI connector connects the analog I/O signals to the shielded cable.
Chapter 3 Signal Connections Table 3-1. BNC Analog I/O Connector Signal Descriptions (Continued) Signal Name Reference +DAC1OUT –DAC1OUT Output +Analog Output Channel 1—This pin supplies the analog non-inverting output channel 1. This signal passes through the internal BNC conductor. –DAC1OUT +DAC1OUT Output –Analog Output Channel 1—This pin supplies the analog inverting output channel 1. This signal passes through the external BNC shell.
Chapter 3 Signal Connections Figure 3-1 describes the pin connections on the BNC-2140 68-pin connector.
Chapter 3 Signal Connections Note This BNC-2140 pin assignment maps to the pin assignment of the DSA device you are connecting to the BNC-2140. Refer to your DSA device user manual for the pin assignments specific to your device connection. Table 3-2 shows the pin assignments for the internal 68-pin I/O connector. Table 3-2.
Chapter 3 Signal Connections The outer shell of the BNC connectors is not GND (0 V). The outer shell of the BNC is not physically connected to the metal box of the BNC-2140. The outer shell is either the inverting differential signal in DIFF mode or is tethered to GND (0 V) through a 50 Ω, 1 W resistor in SE mode. Analog Input Signal Connections The analog input signals for the BNC-2140 device are +ACH<0..3> and –ACH<0..3>.
4 Theory of Operation This chapter contains a functional overview of the BNC-2140.
Chapter 4 Theory of Operation Functional Overview Figure 4-1 is a block diagram of the BNC-2140.
Chapter 4 Theory of Operation Analog Input Circuitry The BNC-2140 has four identical analog input channels. A principal function of the BNC-2140 is to supply a constant current for ICP type accelerometers and microphone preamplifiers. Many accelerometers use piezoelectric materials to generate a charge that is proportional to the acceleration applied. Although these types of accelerometers have certain advantages, they are very suseptable to external noise.
Chapter 4 Theory of Operation Analog Output The BNC-2140 has two analog output channels. The BNC-2140 can also select between DIFF and SE outputs. In DIFF mode, one line connects to the positive output of the channel and the other connects to the negative output of that same channel. You can connect the differential output to either floating or ground-referenced signals.
A Specifications This appendix lists the specifications of the BNC-2140 accessory. All specifications are typical at 25° C unless otherwise noted. All specifications are relative to measurement standards and require a 15 minute warm-up period. Specifications do not include transducer error. Analog Input Voltage Input Number of channels ............................... 4 Maximum input voltage (Signal + common mode voltage).......... Each input should remain within ±42.
Appendix A Specifications Temperature coefficient..........................±127 ppm/° C Voltage compliance ................................24 V Excitation overvoltage protection...........±42.4 V (30 Vrms) powered on or off Analog Output Number of channels................................2, see Caution under Analog Output Signal Connections, in Chapter 3, Signal Connections Output coupling ......................................DC Power Requirement (from DSA board) Power consumption ......................
Customer Communication B For your convenience, this appendix contains forms to help you gather the information necessary to help us solve your technical problems and a form you can use to comment on the product documentation. When you contact us, we need the information on the Technical Support Form and the configuration form, if your manual contains one, about your system configuration to answer your questions as quickly as possible.
Fax-on-Demand Support Fax-on-Demand is a 24-hour information retrieval system containing a library of documents on a wide range of technical information. You can access Fax-on-Demand from a touch-tone telephone at 512 418 1111. E-Mail Support (Currently USA Only) You can submit technical support questions to the applications engineering team through e-mail at the Internet address listed below. Remember to include your name, address, and phone number so we can contact you with solutions and suggestions.
Technical Support Form Photocopy this form and update it each time you make changes to your software or hardware, and use the completed copy of this form as a reference for your current configuration. Completing this form accurately before contacting National Instruments for technical support helps our applications engineers answer your questions more efficiently.
Documentation Comment Form National Instruments encourages you to comment on the documentation supplied with our products. This information helps us provide quality products to meet your needs. Title: BNC-2140 User Manual Edition Date: April 1998 Part Number: 321933A-01 Please comment on the completeness, clarity, and organization of the manual.
Glossary Prefix Meanings Value p- pico 10 –12 n- nano- 10 –9 µ- micro- 10 – 6 m- milli- 10 –3 k- kilo- 10 3 M- mega- 10 6 G- giga- 10 9 t- tera- 10 12 Numbers/Symbols % percent + positive of, or plus – negative of, or minus / per ° degree Ω ohm +5 ς +5 V VDC source signal A A amperes AC alternating current AC coupled allowing the transmission of AC signals while blocking DC signals © National Instruments Corporation G-1 BNC-2140 User Manual
Glossary ACH analog input channel signal A/D analog-to-digital ADC analog-to-digital converter—an electronic device, often an integrated circuit, that converts an analog voltage to a digital number alias a false lower frequency component that appears in sampled data acquired at too low a sampling rate amplification a type of signal conditioning that improves accuracy in the resulting digitized signal and reduces noise amplitude flatness a measure of how close to constant the gain of a circuit re
Glossary C C Celsius channel pin or wire lead to which you apply or from which you read the analog or digital signal. Analog signals can be single-ended or differential. For digital signals, you group channels to form ports. Ports usually consist of either four or eight digital channels.
Glossary D D/A digital-to-analog DAC digital-to-analog converter—an electronic device, often an integrated circuit, that converts a digital number into a corresponding analog voltage or current DAC0OUT analog channel 0 output signal DAC1OUT analog channel 1output signal dB decibel—the unit for expressing a logarithmic measure of the ratio of two signal levels: dB=20log10 (V1/V2), for signals in volts DC direct current DC coupled allowing the transmission of both AC and DC signals default sett
Glossary DNL differential nonlinearity—a measure in least significant bit of the worst-case deviation of code widths from their ideal value of 1 LSB dynamic range the ratio of the largest signal level a circuit can handle to the smallest signal level it can handle (usually taken to be the noise level), normally expressed in decibels E EMC electromechanical compliance F floating signal sources signal sources with voltage signals that are not connected to an absolute reference or system ground.
Glossary I IC integrated circuit ICP Integrated Circuit Piezoelectric—identifies products that operate using a constant current source and returns the output signal in the form of voltage modulation on the same line as the constant current source. IMD intermodulation distortion—the ratio, in dB, of the total rms signal level of harmonic sum and difference distortion products, to the overall rms signal level.
Glossary K k kilo—the standard metric prefix for 1,000, or 103, used with units of measure such as volts, hertz, and meters K kilo—the prefix for 1,024, or 210, used with B in quantifying data or computer memory kS 1,000 samples L LabVIEW laboratory virtual instrument engineering workbench linearity the adherence of device response to the equation R = KS, where R = response, S = stimulus, and K = a constant linearization a type of signal conditioning in which software linearizes the voltage leve
Glossary N NC normally closed, or not connected NIST National Institute of Standards and Technology noise an undesirable electrical signal—Noise comes from external sources such as the AC power line, motors, generators, transformers, fluorescent lights, soldering irons, CRT displays, computers, electrical storms, welders, radio transmitters, and internal sources such as semiconductors, resistors, and capacitors. Noise corrupts signals you are trying to send or receive.
Glossary peak to peak a measure of signal amplitude; the difference between the highest and lowest excursions of the signal pF pico farad—a farad is a unit used to measure capacitance ppm parts per million pts points R relative accuracy a measure in LSB of the accuracy of an ADC. It includes all non-linearity and quantization errors. It does not include offset and gain errors of the circuitry feeding the ADC. resolution the smallest signal increment that can be detected by a measurement system.
Glossary Shannon Sampling Theorem a law of sampling theory stating that if a continuous bandwidth-limited signal contains no frequency components higher than half the frequency at which it is sampled, then the original signal can be recovered without distortion SNR signal-to-noise ratio—the ratio of the overall rms signal level to the rms noise level, expressed in decibels source impedance a parameter of signal sources that reflects current-driving ability of voltage sources (lower is better) and the
Glossary V V volts VDC volts direct current VIH volts, input high VIL volts, input low Vin volts in VOH volts, output high VOL volts, output low Vref reference voltage W waveform multiple voltage readings taken at a specific sampling rate working voltage the highest voltage that should be applied to a product in normal use, normally well under the breakdown voltage for safety margin.
Index Numbers optional equipment, 1-2 to 1-3 overview, 1-1 requirements for getting started, 1-2 unpacking, 1-2 bulletin board support, B-1 +5 V signal, 68-pin connector signal descriptions (table), 3-4 A +ACH<0..3> signal 68-pin connector signal descriptions (table), 3-4 analog connector (table), 3-1 analog input signal connections, 3-5 –ACH<0..
Index I/O connectors, 3-1 to 3-5 68-pin connector signal descriptions (table), 3-4 analog connector signal descriptions (table), 3-1 to 3-2 exceeding maximum ratings (caution), 3-4 to 3-5 pin connections (figure), 3-3 analog output signal connections, 3-5 DGND signal, 68-pin connector signal descriptions (table), 3-4 DIFF configuration analog input circuitry, 4-3 analog input signal connections, 3-5 analog output, 4-4 analog output signal connections, 3-5 setting, 2-1 to 2-2 documentation conventions used
Index switch settings and signal connections (figure), 2-2 signal connections, 3-1 to 3-5 analog input, 3-5 analog output, 3-5 I/O connectors, 3-1 to 3-5 68-pin connector signal descriptions (table), 3-4 analog connector signal descriptions (table), 3-1 to 3-2 exceeding maximum ratings (caution), 3-4 to 3-5 pin connections (figure), 3-3 switch settings and signal connections (figure), 2-2 specifications, A-1 to A-2 analog input, A-1 to A-2 current excitation, A-1 to A-2 voltage input, A-1 analog output, A
