ADLINK cPCI-6208V - Manual (Page 45)

Utility/Calibration
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6.2.3 Voltage Output Calibration
Because there is an internal reference voltage for each DA channel, the
calibration process for each channel is independent. The following
procedure, VRn-1 and VRn-2 are used to represent the full range and
offset of the nth channels. The following is the calibration procedure for
the DA output.
Step 1. Connect the n-th DA output (Vn) to DVM (+) of the digital multi-
meter. Connect the AGND signal to DVM (-).
Step 2. Send the digital value ‘0’ to the DA. Roughly adjust the offset
(trim VR n-2) until the DVM value equals zero.
Step 3. Send the digital value ‘-32767’ to the DA. Adjust VRn-2 until the
DVM value equals to –10V.
Step 4. Send the digital value ‘0’ to the DA again. Precisely adjust the
offset (trim VR n-2) until the DVM value equals zero.
Step 5. Repeat Steps 2-4 until the accuracy is within the application‘s
specifications.
6.2.4 Current Output Calibration
The current output calibration is only available to the cPCI/PCI-6208A. As
the current output channels are controlled by its corresponding voltage
output channels, VR n-1 and VR n-2 are also used to calibrate the n-th
current output channel.
Step 1. Connect the n-th current output (An) to the DVM (A+) of the
digital multi-meter. Connect both junctions of the current load
(typical 250
Ω
) to the DVM (A-) and ground (AGND) respectively.
Step 2. Select the current range with the provided software program.
Example: set the current range to 4~20 mA.
Step 3. Send the digital value ‘0’ to the DA. Adjust the offset (trim VRn-2)
until the current value equals the minimum value of the current
range. Example, adjust to 4mA if the current range is 4~20mA.
Step 4. Send the digital value ‘32767’ to the DA. Adjust for the full range
(trim VR n-1) until the current value equals the maximum value of
the full range. Example, adjust to 20 mA if the current range is
4~20mA.
Step 5. Repeat step 3 and step 4 until the accuracy is within the
application‘s specifications.