National Instruments SCXI-1121 Manuel D’Utilisation

© National Instruments Corporation

8.

Adjust the input potentiometer of the channel of interest until the 
output is 0 ± 6 mV.

9.

Go to the next channel.

To avoid erroneous results when nulling the amplifier, follow these steps in 
the order indicated.

When calibrating the excitation channels, you should always start with the 
voltage excitation and then proceed to the current excitation, because the 
voltage excitation reference is used as a voltage reference for the current 
excitation. The following procedure will show you how to recalibrate your 
module excitation channel to the factory-calibration setting.

1.

Connect a 120 

Ω

 precision resistor to the output of your excitation 

channel. Before connecting this resistor, measure it with a four-wire 
ohmmeter and record the exact value you have measured.

2.

Set up the excitation channel of interest to 3.333 V excitation level.

3.

Connect your DMM leads to the excitation output as close as possible 
to the resistor body.

4.

Adjust the excitation voltage potentiometer until you read 
3.333 V ± 0.04%. 

5.

Set up your channel for 150 µA excitation level.

6.

Adjust the excitation current potentiometer until you read 
(150 µA x R120) V ± 0.04%, where R

 is the measured value of the 

precision resistor.

7.

Go to the next channel.

If you are using an ammeter to calibrate the current excitation level, you do 
not need a low-tempco resistor a simple 120 

Ω

, 1%, 1/4 W, 100 ppm, 

metal-film resistor will do, and you do not need to measure the resistor. 
After following the previous procedure through step 4, follow these steps:

1.

Remove the resistor from the excitation channel.

2.

Set up your channel for 150 µA excitation level.

3.

Connect the ammeter leads to the excitation channel output.

4.

Adjust the excitation current potentiometer until you read 
150 µA ± 0.04%.

5.

Go to the next channel.