National Instruments 24-Bit User's Manual
Contents
1. Figure 3 Connecting Remote Sense Wires to the NI 9237 NI 9237 Operating Instructions and Specifications 12 ni com The actual bridge excitation voltage is smaller than the voltage at the EX and EX leads If you do not use remote sensing of the actual bridge voltage the resulting gain error is R lead for half bridge sensors and bridge 2 R ledd foy full bridge sensors Rbridge If you connect the remote sense signals directly to the bridge resistors the NI 9237 senses the actual bridge voltage and eliminates the gain errors caused by the resistance of the EX and EX leads Shunt Calibration Shunt calibration can correct for errors from the resistance of both the excitation wiring and wiring in the individual resistors of the bridge Remote sensing corrects for resistances from the EX pins on the NI 9237 to the sensor and shunt calibration corrects for these errors and for errors caused by wire resistance within an arm of the bridge Shunt calibration is most useful with quarter bridge National Instruments Corp 13 NI 9237 Operating Instructions and Specifications sensors because there be significant resistance in the wiring to the active resistor in the bridge The NI 9237 shunt calibration circuitry consists of a precision resistor and a software controlled switch Refer to the software help for information about enabling the shunt calibration switch for the NI 9237 Shunt calibration invol2. 2 000 m Pollution Degree IEC 60664 Environmental Management NI is committed to designing and manufacturing products in an environmentally responsible manner NI recognizes that eliminating certain hazardous substances from our products is beneficial to the environment and to NI customers For additional environmental information refer to the NI and the Environment Web page at ni com environment This page contains the environmental regulations and directives with which NI complies as well as other environmental information not included in this document National Instruments Corp 33 NI 9237 Operating Instructions and Specifications Waste Electrical and Electronic Equipment WEEE X EU Customers At the end of the life cycle all products must be sent to a WEEE recycling center For more information about WEEE recycling centers and National Instruments WEEE initiatives visit ni com environment weee BTS mis Riehl CHE ROHS HARA National Instruments A t fa E SS T dd P REMEN REA d da RoHS T National Instruments F EF RoHS TEESE ni com environment rohs china Forinformation about China RoHS compliance go to ni com environment rohs china Calibration You can obtain the calibration certificate and information about calibration services for the NI 9237 at ni com calibration Calibration interval year NI 9237 Opera
3. 100 ppm max Data rate range f using internal master timebase Minm scc e 1 613 kS s Maximum 50 kS s Data rate range f using external master timebase Minimum 390 625 S s Maximum esee 51 3 kS s 256 Data rates EE NET Typical input x25 mV V Scaling coefficient 2 9802 nV V per LSB 1 The data rate must remain within the appropriate data rate range Refer to the Understanding NI 9237 Data Rates section for more information NI 9237 Operating Instructions and Specifications 22 ni com Overvoltage protection between any two 30 V Accuracy Percent of Percent of Reading Range Measurement Conditions Gain Error Offset Error Calibrated typ 25 5 0 0596 0 0596 Calibrated max 40 to 70 C 0 2096 0 2596 Uncalibrated typ 25 5 0 2096 0 196 Uncalibrated max 40 to 70 C 0 60 0 35 Before offset null or shunt calibration Range equals 25 mV V Gait Orit ss tenants 10 ppm C max Offset drift 2 5 V excitation 0 6 u V V per C 3 3 V 0 5 u V V per C 5 V excitation 0 3 u V V per C 10 V excitation 0 2 u V V per C National Instruments Corp 23
4. 9237 Operating Instructions and Specifications Channel to channel matching calibrated Input Signal Gain Phase Frequency fin Typical Maximum Maximum 0 to 1 kHz 0 15 0 3 0 125 KHz fin 1 to 20 kHz 0 496 1 196 Phase nonlinearity Fin 0 to 1 KHz sss 0 001 Fin 0 to 20 KHz 0 1 Input delay 38 4 f 4 8 us Passband Frequency sein 0 45 f Flatness 0 1 dB max Stopband Frequency 0 55 f Rejection 100 dB Alias free bandwidth 0 45 f Oversample rate NI 9237 Operating Instructions and Specifications 24 ni com Rejection at oversample rate f STOKS S rtt 60 dB 640 kHz fre 30 kS 8 ts 90 dB 3 2 MHz Common mode voltage all signals to earth ground 60 VDC CMRR Relative to earth ground fin 0 to 60 2 140 dB Relative to EX fin 0 to 1 2 85 dB SFDR 1 kHz 60 dBFS 106 dB Total Harmonic Distortion THD 1 kHz 20 100 dB 8 kHz 20 dBFS 90 dB Rejection by analog prefilter of signal frequencies at oversample rate Measured with a balanced cable Shielded cables that are not twisted pair may be significantly unbalanced To improve the balance of shielded twisted pair cables NI recommends twistin
5. EEx nC T4 Ex nA T4 or Ex nL T4 equipment NI 9237 Operating Instructions and Specifications 4 ni com Special Conditions for Marine Applications Some modules are Lloyd s Register LR Type Approved for marine applications To verify Lloyd s Register certification visit ni com certification and search for the LR certificate or look for the Lloyd s Register mark on the module Caution To meet radio frequency emission requirements for marine applications use shielded cables and install the system in a metal enclosure Suppression ferrites must be installed on power supply inputs near power entries to modules and controllers Power supply and module cables must be separated on opposite sides of the enclosure and must enter and exit through opposing enclosure walls National Instruments Corp 5 NI 9237 Operating Instructions and Specifications Connecting the NI 9237 The NI 9237 has four RJ 50 receptacles that provide connections for four half or full bridges ChO Ch3 dd 1 SC 2 Al 3 1 Al 4 RS 5 RS 6 EX 7 EX 8 T 9 T 10 SC EX EX Figure 1 NI 9237 Pin Assignments NI 9237 Operating Instructions and Specifications 6 ni com When you connect a half bridge to the NI 9237 you must connect the AI EX and RS signals but you do not connect the AI signal When yo
6. above the stopband frequency and equals the data rate minus the stopband frequency Understanding NI 9237 Data Rates The frequency of a master timebase fy controls the data rate f of the NI 9237 The NI 9237 includes an internal master timebase with a frequency of 12 8 MHz but the module also can accept an external master timebase or export its own master timebase To synchronize the data rate of an NI 9237 with other modules that use master timebases to control sampling all of the modules must share a single master timebase source Refer to the software help for information about configuring the master timebase source for the NI 9237 Visit ni com info and enter cseriesdoc for information about C Series documentation National Instruments Corp 19 NI 9237 Operating Instructions and Specifications The following equation provides the available data rates of the NI 9237 256 Js BE where n is any integer from 1 to 31 However the data rate must remain within the appropriate data rate range Refer to the Specifications section for more information about the data rate range When using the internal master timebase of 12 8 MHz the result is data rates of 50 kS s 25 kS s 16 67 kS s and so on down to 1 613 kS s depending on the value of n When using an external timebase with a frequency other than 12 8 MHz the NI 9237 has a different set of data rates Note The cRIO 9151 Series Expansion chassis does not
7. support sharing timebases between modules Sleep Mode This module supports low power sleep mode Support for sleep mode at the system level depends on the chassis that the module is plugged into Refer to the chassis manual for information about NI 9237 Operating Instructions and Specifications 20 ni com support for sleep mode If the chassis supports sleep mode refer to the software help for information about enabling sleep mode Visit ni com info and enter cseriesdoc for information about C Series documentation Typically when a system is in sleep mode you cannot communicate with the modules In sleep mode the system consumes minimal power and may dissipate less heat than it does in normal mode Refer to the Specifications section for more information about power consumption and thermal dissipation Specifications The following specifications are typical for the range 40 to 70 C unless otherwise noted Input Characteristics Number of channels 4 analog input channels Bridge completion Half and Full Internal Quarter osx d gehen External ADC resolution 24 bits National Instruments Corp 21 NI 9237 Operating Instructions and Specifications Type of Delta Sigma with analog prefiltering Sampling Simultaneous Internal master timebase fy Frequency 12 8 MHz Zire rss
8. 311 210 Russia 7 495 783 6851 Singapore 1800 226 5886 Slovenia 386 3 425 42 00 South Africa 27 0 11 805 8197 Spain 34 91 640 0085 Sweden 46 0 8 587 895 00 Switzerland 41 56 2005151 Taiwan 886 02 2377 2222 Thailand 662 278 6777 Turkey 90 212 279 3031 United Kingdom 44 0 1635 523545 National Instruments NI ni com and LabVIEW are trademarks of National Instruments Corporation Refer to the Terms of Use section on ni com 1ega1 for more information about National Instruments trademarks Other product and company names mentioned herein are trademarks or trade names of their respective companies For patents covering National Instruments products technology refer to the appropriate location Help Patents in your software the patents txt file on your media or the National Instruments Patent Notice at ni com patents 2006 2008 National Instruments Corp All rights reserved 374186C 01 Aug08
9. IIC T4 Europe EEx nC IIC T4 National Instruments Corp 29 NI 9237 Operating Instructions and Specifications Safety Standards This product meets the requirements of the following standards of safety for electrical equipment for measurement control and laboratory use EC 61010 1 EN 61010 1 e UL 61010 1 CSA 61010 1 Note For UL and other safety certifications refer to the product label or the Online Product Certification section Electromagnetic Compatibility This product meets the requirements of the following EMC standards for electrical equipment for measurement control and laboratory use EN 61326 IEC 61326 Class A emissions Basic immunity EN 55011 CISPR 11 Group 1 Class A emissions e AS NZS CISPR 11 Group 1 Class A emissions FCC 47 CFR Part 15B Class A emissions e CES 001 Class A emissions NI 9237 Operating Instructions and Specifications 30 ni com Note For the standards applied to assess the of this N product refer to the Online Product Certification section Note For compliance operate this device with shielded cabling CE Compliance This product meets the essential requirements of applicable European Directives as follows e 2006 95 EC Low Voltage Directive safety e 2004 108 EC Electromagnetic Compatibility Directive EMC Online Product Certification Refer to the product Declaration
10. OPERATING INSTRUCTIONS AND SPECIFICATIONS NI 9237 4 Channel 24 Bit Half Full Bridge Analog Input Module Fran ais Deutsch HAG 80 APX ni com manuals NATIONAL D INSTRUMENTS This document describes how to use the National Instruments 9237 and includes specifications and pin assignments for the NI 9237 Visitni com info and enter rdsoftwareversion to determine which software you need for the modules you are using For information about installing configuring and programming the system refer to the system documentation Visit ni com info and enter cseriesdoc for information about C Series documentation Note The safety guidelines and specifications in this document are specific to the NI 9237 The other components in the system might not meet the same safety ratings and specifications Refer to the documentation for each component in the system to determine the safety ratings and specifications for the entire system Visit ni com info and enter cseriesdoc for information about C Series documentation NI 9237 Operating Instructions and Specifications 2 ni com Safety Guidelines Operate the NI 9237 only as described in these operating instructions Hot Surface This icon denotes that the component may be hot Touching this component may result in bodily injury Safety Guidelines for Hazardous Locations The NI 9237 is suitable for use in Class I Division 2 Groups A B C D T4
11. fer to the Understanding NI 9237 Filtering section for more information about filtering NI 9237 Operating Instructions and Specifications 10 ni com Wiring TEDS Channels Ensure that neither the TEDS data T nor the TEDS return signal is tied in common to any AI signals on the NI 9237 The NI 9237 connects all the signals together internally Visit ni com info and enter the info code rdteds for more information about TEDS sensors NI 9237 Connection Options Wiring resistance can create errors in bridge circuits The NI 9237 provides two mechanisms to correct for these errors remote sensing and shunt calibration Remote Sensing Remote sensing continuously and automatically corrects for errors in excitation leads and generally is most appropriate for half and full bridge sensors Long wire and small gauge wire have greater resistance which can result in gain error The resistance in the wires that connect the excitation voltage to the bridge causes a voltage drop which is a source of gain error The NI 9237 includes remote sensing to compensate for this gain error Connect remote sense wires to the points where the excitation voltage wires connect to the bridge National Instruments Corp 11 NI 9237 Operating Instructions and Specifications circuit Refer to Figure 3 for an illustration of how to connect remote sense wires to the NI 9237 Rbridge 0 0 1 R bridge xps etx
12. g together the AL AI pair the RS RS pair and the pair National Instruments Corp 25 9237 Operating Instructions and Specifications Input noise Density Total Total Excitation nV Vims f 0 to 25 kHz fj 0 to 1 kHz Voltage N1Hz UL V V ms nV V ms 2 5 V 8 1 3 250 3 3 V 6 1 0 190 SV 4 0 6 130 10 V 2 0 3 65 Excitation noise 0 1 mV V ms Crosstalk 110 dB 420 die 100 Excitation Internal voltage 2 5 V 3 3 V 5 0 V 10 0 V Internal power 150 mW max External voltage 2Vtol0V NI 9237 Operating Instructions and Specifications 26 ni com Shunt calibration R SISTANCE ciere eet 100 kQ Resistor accuracy 25 o 110 Q 40 to 70 200 Q MTB Berets otto tenente mes 603 359 hours at 25 Bellcore Issue 2 Method 1 Case 3 Limited Part Stress Method Note Contact NI for specifications at other temperatures or for MIL HDBK 217F specifications Power Requirements Power consumption from chassis Active mode 740 mW max Sleep mode 25 uW max Thermal dissipation at 70 Active mode sssss 740 mW max Sleep mode eene 25 uW max National Instruments Corp 27 9237 Opera
13. hazardous locations Class 1 Zone 2 AEx nC 4 and Ex nC T4 hazardous locations and nonhazardous locations only Follow these guidelines if you are installing the NI 9237 in a potentially explosive environment Not following these guidelines may result in serious injury or death Caution Do not disconnect I O side wires or connectors unless power has been switched off or the area is known to be nonhazardous A Caution Do not remove modules unless power has been switched off or the area is known to be nonhazardous National Instruments Corp 3 9237 Operating Instructions and Specifications Caution Substitution of components may impair A suitability for Class 1 Division 2 A Caution For Zone 2 applications install the system in an enclosure rated to at least IP 54 as defined by 60529 and EN 60529 A Caution For Zone 2 applications connected signals must be within the following limits Capacitance 0 2 UF max Inductance 80 mH max Special Conditions for Hazardous Locations Use in Europe This equipment has been evaluated as EEx nC IIC T4 equipment under DEMKO Certificate No 03 ATEX 0324020X Each module is marked x II 3G and is suitable for use in Zone 2 hazardous locations If you are using the NI 9237 in Gas Group IIC hazardous locations or in ambient temperatures of 40 C lt Ta 70 C you must use the device in an NI chassis that has been evaluated as
14. itation voltages as needed to stay below 150 mW total power 5 The power consumed by a single bridge is pa where R is the total resistance of the bridge For a quarter or half bridge R is equal to two times the resistance of each element For a full bridge R is equal to the resistance of each element National Instruments Corp 15 9237 Operating Instructions and Specifications The 150 mW limit allows you to power half and full bridges as follows e Four 350 Q half bridges at 5 0 V e Four 350 Q full bridges at 3 3 V e Four 120 Q half bridges at 2 5 V If you need an excitation voltage that causes more than 150 mW to dissipate across all the bridges use the EX and EX terminals on the external excitation voltage connector to connect an external excitation source to the NI 9237 Understanding NI 9237 Filtering The NI 9237 uses a combination of analog and digital filtering to provide an accurate representation of in band signals while rejecting out of band signals The filters discriminate between signals based on the frequency range or bandwidth of the signal The three important bandwidths to consider are the passband the stopband and the alias free bandwidth The NI 9237 represents signals within the passband as quantified primarily by passband flatness and phase nonlinearity signals that appear in the alias free bandwidth are either unaliased signals NI 9237 Operating Instructions and Specifications 16
15. ni com or signals that have been filtered by at least the amount of the stopband rejection Passband The signals within the passband have frequency dependent gain or attenuation The small amount of variation in gain with respect to frequency is called the passband flatness The digital filters of the NI 9237 adjust the frequency range of the passband to match the data rate Therefore the amount of gain or attenuation at a given frequency depends on the data rate Figure 4 shows typical passband flatness for the NI 9237 National Instruments Corp 17 NI 9237 Operating Instructions and Specifications 0 025 0 000 Sg 0 025 0 050 0 0 1 0 2 0 3 0 4 0 5 Frequency Data Rate Figure 4 Typical Passband Flatness for the NI 9237 Stopband The filter significantly attenuates all signals above the stopband frequency The primary goal of the filter is to prevent aliasing Therefore the stopband frequency scales precisely with the data NI 9237 Operating Instructions and Specifications 18 ni com rate The stopband rejection is the minimum amount of attenuation applied by the filter to all signals with frequencies within the stopband Alias Free Bandwidth Any signal that appears in the alias free bandwidth of the NI 9237 is not an aliased artifact of signals at a higher frequency The alias free bandwidth is defined by the ability of the filter to reject frequencies
16. of Conformity DoC for additional regulatory compliance information To obtain product certifications and the DoC for this product visit ni com certification search by module number or product line and click the appropriate link in the Certification column National Instruments Corp 31 NI 9237 Operating Instructions and Specifications Shock and Vibration To meet these specifications you must panel mount the system Operating vibration Random IEC 60068 2 64 5 Sms 10 to 500 Hz Sinusoidal 60068 2 6 5 g 10 to 500 Hz Operating shock 60068 2 27 30 g 11 ms half sine 50 g 3 ms half sine 18 shocks at 6 orientations Environmental National Instruments C Series modules are intended for indoor use only but may be used outdoors if installed in a suitable enclosure Refer to the manual for the chassis you are using for more information about meeting these specifications Operating temperature IEC 60068 2 1 IEC 60068 2 2 40 to 70 Storage temperature IEC 60068 2 1 IEC 60068 2 2 40 to 85 C Ingress IP 40 NI 9237 Operating Instructions and Specifications 32 ni com Operating humidity IEC 60068 2 56 10 to 9096 RH noncondensing Storage humidity IEC 60068 2 56 5 to 9596 RH noncondensing Maximum altitude
17. ting Instructions and Specifications Physical Characteristics If you need to clean the module wipe it with a dry towel Weishit hte derart 152 g 5 4 oz Safety Safety Voltages Connect only voltages that are within the following limits Between any two 30 V max Isolation Channel to channel None Channel to earth ground 60 VDC Measurement Category I Withstand 1 000 Vms verified by a5 s dielectric withstand test Measurement Category I is for measurements performed on circuits not directly connected to the electrical distribution system referred to as MAINS voltage MAINS is a hazardous live electrical supply system that powers equipment This category is for NI 9237 Operating Instructions and Specifications 28 ni com measurements of voltages from specially protected secondary circuits Such voltage measurements include signal levels special equipment limited energy parts of equipment circuits powered by regulated low voltage sources and electronics Caution Do not connect the NI 9237 to signals or use for measurements within Measurement Categories II or IV Hazardous Locations US risen Class I Division 2 Groups A B C D T4 Class I Zone 2 AEx nC IIC T4 Canada 0 1 Class I Division 2 Groups A B C D T4 Class I Zone 2 Ex nC
18. ting Instructions and Specifications 34 ni com Where to Go for Support The National Instruments Web site is your complete resource for technical support At com support you have access to everything from troubleshooting and application development self help resources to email and phone assistance from NI Application Engineers National Instruments corporate headquarters is located at 11500 North Mopac Expressway Austin Texas 78759 3504 National Instruments also has offices located around the world to help address your support needs For telephone support in the United States create your service request at ni com support and follow the calling instructions or dial 512 795 8248 For telephone support outside the United States contact your local branch office Australia 1800 300 800 Austria 43 662 457990 0 Belgium 32 0 2 757 0020 Brazil 55 11 3262 3599 Canada 800 433 3488 China 86 21 5050 9800 Czech Republic 420 224 235 774 Denmark 45 45 76 26 00 Finland 358 0 9 725 72511 France 01 57 66 24 24 Germany 49 89 7413130 India 91 80 41190000 Israel 972 3 6393737 Italy 39 02 41309277 Japan 0120 527196 National Instruments Corp 35 NI 9237 Operating Instructions and Specifications Korea 82 02 3451 3400 Lebanon 961 0 1 33 28 28 Malaysia 1800 887710 Mexico 01 800 010 0793 Netherlands 31 0 348 433 466 New Zealand 0800 553 322 Norway 47 0 66 90 76 60 Poland 48 22 3390150 Portugal 351 210
19. u connect a full bridge you must connect the AI EX and RS signals Refer to Figure 2 for an illustration of how to connect half and full bridges to the NI 9237 5 Note You can use a quarter bridge with the NI 9237 if you add a resistor externally to create half bridge You also can use a quarter bridge with the NI 9237 if you use the NI 9944 or NI 9945 Quarter Bridge Completion Accessory Visit ni com and search for the NI 9944 and NI 9945 Quarter Bridge Completion Accessories for more information about these accessories and how to purchase them Note National Instruments does not recommend using an RJ 45 cable with the NI 9237 because it can physically damage pins 1 and 10 on the device and thus permanently disable shunt calibration no matter what connector you use National Instruments Corp 7 9237 Operating Instructions and Specifications The NI 9237 has a four terminal external excitation voltage source connector You can use the and EX terminals on the connector to connect one external excitation voltage source to the module You can use the additional and EX terminals on the connector to wire multiple NI 9237 modules together in a daisy chain 5 Note When you insert or remove a new sensor from the NI 9237 slight changes in the excitation voltages can cause mismatch between the internal half bridge completion resistors and the half bridge sensors which results in change in the meas
20. urement offsets National Instruments recommends performing bridge calibrations of quarter or half bridge sensors after connecting all sensors to the NI 9237 and after removing or attaching any additional sensor Visit n com info and enter the info code rdw9237 for more information about changes in voltage offsets in the NI 9237 NI 9237 Operating Instructions and Specifications 8 ni com TEDS Figure 2 Connecting a Half or Full Bridge to the NI 9237 National Instruments Corp 9 NI 9237 Operating Instructions and Specifications Each channel on the NI 9237 has an independent 24 bit and an input amplifier that enable you to sample signals from all four channels simultaneously The NI 9237 is isolated from earth ground However the individual channels are not isolated from each other The EX EX and T signals are common among all channels You can connect the NI 9237 to a device that is biased at any voltage within the NI 9237 rejection range of earth ground Refer to the Specifications section for more information about the common mode rejection ratio CMRR You also can connect floating signals to the NI 9237 If you connect floating signals to the NI 9237 National Instruments recommends connecting the EX signal to the earth ground or shield for better noise rejection The NI 9237 also includes filters to prevent aliasing The filters on the NI 9237 filter according to the data rate Re
21. ves simulating the input of strain by changing the resistance of an arm in the bridge by some known amount This is accomplished by shunting or connecting a large resistor of known value across one arm of the bridge creating a known strain induced change in resistance You can then measure the output of the bridge and compare it to the expected voltage value You can use the results to correct gain errors in the entire measurement path or to simply verify general operation to gain confidence in the setup Use a stable signal which is typically the unloaded state of the sensor first with the shunt calibration switch off and then again with the switch on The difference in these two measurements provides an indication of the gain errors from wiring resistances You can design the software application to correct subsequent readings for this gain error NI 9237 Operating Instructions and Specifications 14 ni com Excitation Voltages Although the sensor industry does not recognize a single standard excitation voltage level excitation voltage levels of between 2 5 V and 10 V are common You can program the NI 9237 to supply 2 5 V 3 3 V 5 V or 10 V of excitation voltage and the module can provide up to 150 mW of excitation power Unless you supply external excitation voltage National Instruments recommends that you set the excitation voltage to a value that keeps the total power below 150 mW The NI 9237 automatically reduces internal exc
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