National Instruments Isolated Analog Input Modules SCC-AI14 User Manual

Page 15

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15

SCC-AI Series Isolated Analog Input Modules

9.

Adjust the trimpot labeled Gain located on the top of the SCC-AIXX.
If the value you obtained in step 8 is less than the input voltage, turn
the trimpot clockwise to increase the gain. If it is greater than the input
voltage, turn the trimpot counterclockwise to decrease the gain.

10. Repeat steps 4 through 9 until the difference you get in step 8 equals

the Input Voltage Required value shown in Table 1-3; in this example
the value is 8 V using an SCC-AI03.

For example, assume that you have an SCC-AI03 module. You first connect
8 VDC to the input of CH(X). The E Series DAQ device reads 8.05 V as the
SCC output. You then connect 0 VDC to the input of CH(X) and the
E Series DAQ device reads –0.01 V as the SCC output. You subtract these
readings, 8.05 – (–0.01)

= 8.06, getting a difference of 8.06 V. Because this

difference is not equal to 8 V, you must adjust the gain trimpot and repeat
the procedure until the difference in outputs equals 8 V.

Note

In this example there can be an offset voltage such that the final readings are 8.01 V

and 0.01 V for a difference of 8 V. The gain trimpot adjusted in step 9 of the previous
procedure adjusts only for gain errors and does not compensate for this offset voltage.

Complete the following steps to adjust the offset voltage of the SCC-AIXX.

1.

Select the desired SCC-AIXX channel on the E Series DAQ device.

2.

Set the gain on the E Series DAQ device so that the input range
is

±10 V.

3.

Connect the screw terminals of your desired channel on the SCC-AIXX
together.

4.

Using your software, have the E Series DAQ device read the channel.

5.

If the value read is not equal to 0.00 V, adjust the appropriate trimpot
located on the top of the SCC-AIXX, labeled Offset. Turn the trimpot
clockwise to increase the offset.

6.

Repeat steps 4 and 5 until the voltage read in step 4 equals 0.00 V.

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