National Instruments SCXI-1520, Calibration Procedure

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SCXI-1520 Calibration Procedure 14 ni.com
Offset Calibration Constants
1. Call
SCXI_Calibrate
and set the following parameters:
• SCXIChassisID —The value assigned by MAX
• moduleSlot —1
• moduleChan —The number of the channel you want to calibrate
• opCode —0
• calibrationArea —0
• SCXIgain —1
• refVoltage —1
• DAQdevice —The value assigned by MAX
• DAQchan —0
2. Repeat step 1 for each of the remaining channels.
Excitation Calibration Constants
Note This adjustment is not needed for the 0.0 V excitation.
1. Call
SCXI_Adv_Module_Read
to get the value of the 2.5 V reference
voltage on the SCXI-1520. Use the following parameters:
• SCXIchassisID —The value assigned by MAX
• slot —1
• moduleClass —2
• address —3
• numBytes —4
• data —The array that returns the value of the SCXI-1520 2.5 V
reference voltage. The data is returned as 4 bytes in a 4-element
array stored little-endian.
• whichAccess —0
• regMethod — –1
• subAddress —104
2. Calculate the excitation calibration constant to be written to the
module. Use the following equation:
ExcitationAdjust = V
exm
/ Vref _2.5
where
V
exm
is the measured value of the excitation voltage from step 5
of the Verifying Voltage Excitation section
Vref_2.5 is the value of the 2.5 V reference voltage from step 1