National Instruments SCC-AO10 User Manual page 7

Using the SCC-AO10
Scaling Voltage Measurements
Isolated Ground Reference
Calibrating Gain and Offset Errors
© National Instruments Corporation
The SCC-AO10 is a ±10 V isolated analog output module. The output
voltage is controlled by an E Series DAQ device AO output channel,
AO (X). The relationship between the AO (X) voltage level and the output
voltage level of the SCC-AO10 is a one-to-one linear relationship. That is,
where
V is the AO 0 voltage level
AO (X)
V is the SCC-AO10 voltage output in volts
AO10
Each SCC-AO10 module is referenced to its own isolated ground. Each
isolated ground can have up to 300 V of common-mode voltage between
itself and any other channel ground or chassis ground. Refer to the
Connecting the SCC-AO10 to a Load
ground in signal connections.
The SCC-AO10 is calibrated at the factory before shipment. To adjust the
gain and offset of the SCC-AO10 in your system using an E Series DAQ
device, you need a voltage meter and a 1/8 in. flathead screwdriver. Before
adjusting the SCC-AO10, allow 30 minutes for the DAQ device to warm
up to its nominal operating temperature.
To adjust the gain and offset of the SCC-AO10, complete the following
steps:
1. Disconnect the load from the SCC-AO10 you want to calibrate.
2. Set an output range of –10 to +10 V for AO (X), the E Series DAQ
device channel connected to the SCC-AO10.
3. Connect the negative lead of the voltmeter to the isolated ground
terminal (pin 1) and the positive lead to the voltage output terminal
(pin 2 or 3) of the SCC-AO10.
4. Using your software, set AO (X) to output 0 VDC.
5. Adjust the offset potentiometer on the top of the SCC-AO10 until the
voltmeter reads 0 VDC ±100 µV. The offset is now calibrated.
6. Using your software, have AO (X) output 9.9 VDC.
= V
V
AO (X) AO10
section for ways to use the isolated
7 SCC-AO10 Isolated Analog Output Module User Guide