Adjusting Current Excitation; Verifying Adjusted Values - National Instruments SCXI-1121 Calibration Procedure

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This step calibrates the 450 µA level at the same time, but the accuracy achieved is

Note

limited to ±0.2%. To achieve better accuracy at the 450 μA level, follow steps 1 through 4

but set the excitation level to 450 µA instead of 150 µA. If you do so, the 150 µA level of

this channel will then be calibrated to ±0.2% instead of to ±0.04%. In the factory, the

SCXI-1121 is calibrated for 150 µA.

Note

If the SCXI-1121 fails after calibration, return it to NI for repair or replacement. For

more information about how to contact NI for repair or replacement, refer to the Technical

Support Information document.

Adjusting Current Excitation

Complete the following steps to adjust the current excitation:

Remove the resistor from the excitation channel if you have not

already done so.

Configure the channel for 0.150 mA current excitation level.

Set the DMM to current mode, and connect it to the excitation channel

output you want to adjust.

Adjust the excitation current potentiometer until the current reading

falls between 0.150060 mA and 0.149940 mA. Refer to Figure 3 for

the potentiometer location and Table 11 for the potentiometer

reference designator.

Repeat steps 1 through 4 for all remaining channels.

You have completed adjusting the current excitation channels.

After completing the adjustments, it is important to verify the analog

input operation, the voltage excitation, and the current excitation again by

repeating the steps listed in the

adjusted values ensures that the SCXI-1121 is operating within its test

limits after adjustments.

Verification

Procedure. Verifying the

SCXI-1121 Calibration Procedure

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