National Instruments SCXI -1122 User Manual

Also see for SCXI-1122: Getting started Quick start guide Quick start guide Instructions for safe use

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National Instruments SCXI -1122 User Manual Manual pdf 46 page image

Calibration Chapter 5SCXI-1122 User Manual 5-4 © National Instruments CorporationExcitation CalibrationWhen using the excitation channels, you must retrieve the correction factors for the current andvoltage from the EEPROM before using them in your transducer conversion formulas. Refer toyour software user manual for how to use the SCXI_Cal_Constants function or VI toperform this task.You do not need to read the following section if you are going to use the factory-determinedcorrection factors and you are using National Instruments software.If you want to determine a new set of voltage excitation calibration constants and you are usingNational Instruments software, use the following procedure:1. Connect a 15 Ω resistor to the excitation channel.2. Connect the DMM across the 15 Ω load and measure the voltage.3. Pass this voltage to the SCXI_Cal_Constants function or VI.To determine the current excitation calibration constants, follow this procedure:1. Set your DMM to DC current measurements.2. Connect the DMM across the IEX+ and IEX- terminals and measure the current.3. Pass this current to the SCXI_Cal_Constants function or VI.Note: When calibrating your system, you must verify that your offsets, gain errors, andexcitation errors do not exceed the ranges listed in Table 5-1.Table 5-1. Maximum Allowable Error RangesError Type Error RangeAll gains ±2%Offset at G = 0.01 ±40 mVOffset at G = 0.02 ±40 mVOffset at G = 0.05 ±50 mVOffset at G = 0.1 ±50 mVOffset at G = 0.2 ±50 mVOffset at G = 0.5 ±50 mVOffset at G = 1 ±40 mVOffset at G = 2 ±40 mVOffset at G = 5 ±50 mVOffset at G = 10 ±50 mVOffset at G = 20 ±50 mVOffset at G = 50 ±50 mVOffset at G = 100 ±60 mVOffset at G = 200 ±70 mVOffset at G = 500 ±100 mVOffset at G = 1,000 ±200 mVOffset at G = 2,000 ±400 mVCurrent excitation ±3%Voltage excitation ±1%