National Instruments SCXI-1120/D, Calibration Procedure

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© National Instruments Corporation 13 SCXI-1120/D Calibration Procedure
Adjusting Offset Null Values of the Module
Complete the following steps to adjust the offset null value:
1. Set the channel gain on all channels to a gain of 1. Set the filter value
to 4 Hz for the SCXI-1120 module or 4.5 kHz for the SCXI-1120D
module. Refer to the
Setting Up the Module section in this document
for information on how to set the channel gain.
2. Connect the calibrator to the analog input channel you want to adjust,
starting with channel 0. Refer to Table 5 to determine the pins on the
96-pin front connector that correspond to the positive and negative
inputs of the specified channel. For example, the positive input for
channel 0 is pin A32, which is labeled
CH0+ . The negative input for
channel 0 is pin C32, which is labeled CH0– .
3. Connect the DMM to the output of the same channel to which the
calibrator was connected in step 2. Refer to Figure 4 to determine the
pins on the 50-pin rear connector that correspond to the positive and
negative outputs for the specified channel. 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– .
4. Set the calibrator to output 0.0 V.
5. Adjust the output potentiometer of the channel until the DMM reading
is 0 ±3.0 mV. Refer to Figure 3 for the potentiometer location and
Table 6 for the potentiometer reference designator.
6. Set the channel gain on all channels to 1000.0.
Table 6. Calibration Potentiometers Reference Designators
Input Channel Number Input Null Output Null
0 R08 R24
1 R10 R25
2 R12 R26
3 R14 R27
4 R16 R28
5 R18 R29
6 R20 R30
7 R21 R31