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Chapter 8
Calibrating the Analog Input Subsystem
This section describes how to use the DT9812 Series Calibration Utility to calibrate the analog
input subsystem of a DT9812-10V, DT9812-10V-OEM, DT9812A, DT9813-10V, DT9813A,
DT9814-10V, or DT9814A module.
Connecting a Precision Voltage Source
To calibrate the analog input circuitry, you need to connect an external precision voltage
source to Analog In 0 (AD Ch0) of the module.
Using the Auto-Calibration Procedure
Auto-calibration is the easiest to use and is the recommended calibration method. To
auto-calibrate the analog input subsystem, do the following:
1. Select the A/D Configuration tab of the DT9812 Series Calibration Utility.
2. Set the voltage supply on AD Ch0 to 0 V.
3. Click Start Auto Calibration.
4. Check that the supplied voltage to AD Ch0 is 0V, and then click OK.
5. Check that the supplied voltage to AD Ch0 is +9.375V, and then click OK.
6. Click OK to finalize the analog input calibration process.
Note: At any time, you can click Restore Factory Settings to reset the A/D calibration
values to their original factory settings. This process will undo any auto or manual calibration
settings.
Using the Manual Calibration Procedure
If you want to manually calibrate the analog input circuitry instead of auto-calibrating it, do
the following:
1. Adjust the offset as follows:
98
A message appears notifying you to verify that 0 V is applied to AD Ch0.
The offset value is calibrated. When the offset calibration is complete, a message appears notifying
you to set the input voltage of AD Ch 0 to +9.375 V.
The gain value is calibrated.
a. Verify that 0V is applied to AD Ch0, and that A/D Channel Select is set to Channel 0.
The current voltage reading for this channel is displayed in the A/D Value window.
b. Adjust the offset by entering values between 0 and 63 in the Offset edit box, or by
clicking the up/down buttons until the A/D Value is 0 V.
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