National-instruments Isolated Current Output Module SCC-CO20 Manuel d'utilisateur télécharger pdf (Page 8)

SCC-CO20 Isolated Current Output Module User Guide 8 ni.com

Figure 5. Connecting the SCC-CO20 to a Grounded External Loop Supply

and a Grounded Load

For information about how to configure the SCC-CO20 module using

NI-DAQmx, refer to the SCC Quick Start Guide.

Calibrating Gain and Offset Errors

The SCC-CO20 is calibrated at the factory before shipment. If you want

to adjust the gain and offset of the SCC-CO20 in your system using an

E/M Series DAQ device, you need a current meter (ammeter) with an

accuracy of at least ±2 μA.

To adjust the gain and offset of the SCC-CO20, complete the following

steps:

1. Disconnect the load from the SCC-CO20 you want to calibrate.

2. Set an output range of 0 to 10 V for AO (X), the E/M Series DAQ

device channel connected to the SCC-CO20.

3. Connect the negative lead of the ammeter to the current sink (pin 2)

and the positive lead to the current supply (pin 3) of the SCC-CO20.

4. Using your software, have AO (X) output 10 mVDC.

5. Adjust the offset potentiometer on the top of the SCC-CO20 until the

ammeter reads 20 μA. The offset is now calibrated.

6. Using your software, have AO (X) output 9 VDC.

7. Adjust the gain potentiometer on the top of the SCC-CO20 until the

ammeter reads 18 mA. The gain is now calibrated.

Load

–

20 mA

SINK

SCC-CO20

ISO GND

–

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National-instruments Isolated Current Output Module SCC-CO20 Manuel d'utilisateur Page 8