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CALIBRATION PROCEDURE
SCXI -1122
™
Contents
This document contains information and step-by-step instructions for
calibrating the National Instruments SCXI-1122 module.
Introduction ............................................................................................. 2
What Is Calibration? ........................................................................ 2
Why Should You Calibrate? ............................................................ 2
How Often Should You Calibrate? .................................................. 2
Equipment and Other Test Requirements ............................................... 2
Test Equipment ................................................................................ 2
Instruments ............................................................................... 3
Connectors ................................................................................ 3
Software and Documentation........................................................... 3
Software.................................................................................... 3
Documentation.......................................................................... 3
Test Conditions ................................................................................ 4
Calibration............................................................................................... 4
Setting Up the Module ..................................................................... 5
Verifying the Operation of the Module ........................................... 5
Verifying Analog Input Offsets ................................................ 5
Verifying Excitation Limits...................................................... 9
Adjusting the Module ...................................................................... 10
Adjusting Gain and Offset Errors ............................................. 10
Adjusting Calibration Constants............................................... 13
Adjusting Excitation Limits...................................................... 14
Verifying Adjusted Values .............................................................. 15
Test Limits .............................................................................................. 15
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Summary of Contents for National Instruments SCXI -1122
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Page 1: Table Of Contents
CALIBRATION PROCEDURE SCXI -1122 ™ This document contains information and step-by-step instructions for calibrating the National Instruments SCXI-1122 module. Contents Introduction ..................... 2 What Is Calibration? ................ 2 Why Should You Calibrate? ............2 How Often Should You Calibrate? ..........2 Equipment and Other Test Requirements .......... -
Page 2: Introduction
Introduction What Is Calibration? Calibration consists of verifying the measurement accuracy of a module and adjusting for any measurement error. Verification is measuring the performance of the module and comparing these measurements to the factory specifications. During calibration, you supply and read voltage levels using external standards, then you adjust the module calibration constants. -
Page 3: Instruments
• Traditional NI-DAQ User Manual The Traditional NI-DAQ Function Reference Help and the Traditional NI-DAQ User Manual contain detailed information about using Traditional NI-DAQ (Legacy). The help file includes detailed information about the © National Instruments Corporation SCXI-1122 Calibration Procedure... -
Page 4: Test Conditions
NI-DAQ devices. It also includes detailed information about creating applications that use Traditional NI-DAQ (Legacy). You can access the user manual by selecting Start»All Programs»National Instruments» NI-DAQ»Traditional NI-DAQ User Manual. These documents are your primary references for writing your calibration utility. -
Page 5: Setting Up The Module
Call to set the E Series DAQ device in bipolar mode. AI_Configure Set the following parameters: • deviceNumber—The value assigned by MAX • chan—0 • inputMode—0 • inputRange—0 • polarity—0 • driveAIS—0 © National Instruments Corporation SCXI-1122 Calibration Procedure... - Page 6 Call to enable dithering on the E Series DAQ device. MIO_Config Set the following parameters: • deviceNumber—The value assigned by MAX • dither—1 • useAmux—0 Call to configure the filter mode of the SCXI_Configure_Filter SCXI-1122 module. Set the following parameters: •...
- Page 7 Column A Column B Column C CH0+ RSVD CH0– CH1+ CH1– CH2+ CH2– CH3+ CH3– CH4+ IEX+ CH4– CH5+ IEX– CH5– CH6+ VEX+ CH6– CH7+ SENSE+ CH7– CH8+ SENSE– CH8– CH9+ VEX– CH9– CH10+ © National Instruments Corporation SCXI-1122 Calibration Procedure...
- Page 8 Table 1. SCXI-1122 Front Connector Pin Assignments (Continued) Pin Number Column A Column B Column C VEX/2 CH10– CH11+ CH11– CH12+ +5 V CH12– CH13+ CH13– CH14+ TEMP+ CH14– CH15+ TEMP– CH15– NC — No connect 12. Set the calibrator voltage to the Test Point value in Table 3 that corresponds to the gain from step 10.
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Page 9: Verifying Excitation Limits
Compare the DMM reading to the upper and lower limits for voltage excitation shown in Table 2. If the reading falls between the Upper Limit and Lower Limit values, the SCXI-1122 module passed the test. © National Instruments Corporation SCXI-1122 Calibration Procedure... -
Page 10: Adjusting The Module
Table 2. Excitation Test Limits Excitation Type Test Point Upper Limit Lower Limit Voltage 3.333 V 3.3343 V 3.3317 V Current 1.00 mA 1.0004 mA 0.9996 mA Set the DMM to current mode and connect it between the IEX+ and IEX–... - Page 11 For example, the positive output for channel 0 is pin 3, which is labeled MCH0+. The negative output for channel 0 is pin 4, which is labeled MCH0–. © National Instruments Corporation SCXI-1122 Calibration Procedure...
- Page 12 AOGND AOGND MCH0+ MCH0– OUTREF DIGGND SERDATIN SERDATOUT DAQD*/A SLOT0SEL DIGGND SCANCLK SERCLK RSVD RSVD Figure 1. SCXI-1122 Rear Connector Pin Assignments Set the calibrator voltage to the test point value specified by the Test Point entry on Table 3. Read the voltage from the DMM.
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Page 13: Adjusting Calibration Constants
SCXIgain—The appropriate gain for the pair of constants you are about to save on the SCXI-1122 module • DAQboard—Device number assigned by MAX • DAQChan—0 • DAQGain—1 for 16-bit devices, –1 for 12-bit devices • Tbgain—1 © National Instruments Corporation SCXI-1122 Calibration Procedure... -
Page 14: Adjusting Excitation Limits
• volt1 and volt2—The first and second calibrator voltage readings for the gain values you are saving on the SCXI-1122 module • binary1 and binary2—The first and second binary readings for the gain values you are saving on the SCXI-1122 module •... -
Page 15: Verifying Adjusted Values
Table 3 contains test limits for the SCXI-1122 module. If the module was calibrated within the last year, the output from the module should fall between the Upper Limit and Lower Limit values. © National Instruments Corporation SCXI-1122 Calibration Procedure... - Page 16 Table 3. SCXI-1122 Module Test Limits 4 Hz Ranges 4 kHz Ranges Gain Test Point (V) Upper Limit (V) Lower Limit (V) Upper Limit (V) Lower Limit (V) 245.0000 245.6546212 244.3453788 245.6645421 244.3354579 0.0100 0.0000 0.280261209 –0.280261209 0.290182066 –0.290182066 –245.0000 –244.3453788 –245.6546212 –244.3354579...
- Page 17 –0.002461098 The test point is the voltage value that you use for verification purposes. National Instruments, NI, ni.com, and LabVIEW are trademarks of National Instruments Corporation. Refer to the Terms of Use section on ni.com/legal for more information about National Instruments trademarks.
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