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National Instruments Corporation
7
SCC-AI Series Isolated Analog Input Modules User Guide
Using the SCC-AI when Scaling Voltage Measurements
If you configured the SCC-AI using Measurement & Automation Explorer
(MAX) and you are using NI-DAQmx, the voltage reading you get from the
E/M Series DAQ device accounts for the voltage scaling effect of the
SCC-AI. Otherwise, because the voltage measurement from the E/M Series
DAQ device is scaled by the gain given in Table 1, you must divide the
voltage reading returned by the E/M Series DAQ device by this gain to get
the correct input voltage.
Calibrating Gain and Offset Errors
The SCC-AI is calibrated at the factory before shipment. If you want to
adjust the gain of the SCC-AI in your system using your E/M Series DAQ
device, you need a voltage source that is several times more accurate than
the SCC itself and capable of providing the DC voltage shown in Table 2.
Gain Adjustment
To adjust the gain of the SCC-AI, complete the following steps:
1.
Select the desired SCC-AI channel on the E/M Series DAQ device.
2.
Set the gain on the E/M Series DAQ device so that its input range is
±10 V.
3.
Connect the voltage source to the screw terminals of the desired
channel on the SCC-AI.
4.
Apply the voltage given in Table 2 that corresponds to the SCC-AI
module. For example, if you have an SCC-AI03, you must apply
8 VDC.
Table 2.
SCC-AI Input Voltage Requirements
Module
Input Range
SCC-AI01
40 V
SCC-AI02
16 V
SCC-AI03
8 V
SCC-AI04
4 V
SCC-AI05
800 mV
SCC-AI06
80 mV
SCC-AI07
40 mV
SCC-AI13
8 V
SCC-AI14
4 V
