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, National Instruments

, ni.com

, NI-DAQ

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are trademarks of National Instruments Corporation. Product and company

names mentioned herein are trademarks or trade names of their respective companies.

370267A-01

©

Copyright 2000 National Instruments Corp. All rights reserved.

July 2000

CALIBRATION PROCEDURE

SCXI -1104

Introduction

This document contains information and step-by-step instructions for
verifying and calibrating the National Instruments SCXI-1104 signal
conditioning module.

What Is Calibration?

Calibration is a procedure of reading offset and gain errors from a device
and updating special analog calibration circuitry that corrects these errors.
National Instruments calibrates every SCXI-1104 module at the factory.
During the factory calibration process, the calibration constants are stored
in the non-volatile memory of the device. These values are loaded from
memory and used as needed by the device.

Why Should You Calibrate?

Offset and gain errors drift with time and temperature, which could
invalidate the factory-set calibration of a device. Calibration restores the
device to its specified accuracy.

How Often Should You Calibrate?

The measurement accuracy requirements of your application
determine how often you should calibrate your SCXI-1104 module.
National Instruments recommends you perform a complete calibration
at least once every year. You can shorten this interval to six months or
90 days, based on the demands of your application.

Summary of Contents for SCXI-1104

Page 1: ...rcuitry that corrects these errors National Instruments calibrates every SCXI 1104 module at the factory During the factory calibration process the calibration constants are stored in the non volatile...

Page 2: ...need a connector block such as the National Instruments SCXI 1300 a shielded 68 pin connector cable a 50 pin ribbon cable a 50 pin breakout box and an SCXI adapter These components give easy access to...

Page 3: ...w these guidelines to optimize the connections and the environment during calibration Keep connections to the SCXI module as short as possible Long cables and wires can act as antennae which pick up e...

Page 4: ...ete the following steps to verify the operation of your SCXI 1104 1 Read the Test Conditions section earlier in this document 2 Refer to Table 1 at the end of this document to see the test specificati...

Page 5: ...tor to the CH0 and CH0 inputs 8 Call SCXI_Single_Chan_Setup to configure the module for single channel measurements Set the following parameters SCXIchassisID The value obtained from Measurement Autom...

Page 6: ...XI 1104 Note If all channels fall within the upper and lower limits your module does not need to be adjusted Adjusting Gain and Offset Errors and Calibration Constants This section contains step by st...

Page 7: ...positive and negative inputs of the specified channel For example the positive input for channel 0 is pin C32 which is labeled CH0 The negative input for channel 0 is pin B32 which is labeled CH0 If...

Page 8: ...and binary2 with volt2 for later use 15 Repeat step 4 through 14 for the remaining channels you want to adjust Adjusting Calibration Constants Complete the following steps to adjust the calibration co...

Page 9: ...on the SCXI 1104 calConst1 and calConst2 These are return values 2 Repeat step 1 changing calibrationArea to 1 3 Repeat step 1 changing calibrationArea to 3 4 Repeat steps 1 through 3 for the next cha...

Page 10: ...NC NC CGND 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 A CH31 CH30 CH29 CH28 CH27 CH26 CH25 CH24 CH23 CH22 CH21 CH20 CH19 CH18 CH17 CH16 CH15 CH14 CH13 CH12...

Page 11: ...er Limit and Lower Limit values Table 1 SCXI 1104 Specifications Ranges Gain Test Point V Upper Limit V Lower Limit V 0 100 41 8000 41 8219 41 7781 0 0000 0 0010 0 0010 41 8000 41 7781 41 8219 NC NC N...

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