Data Translation DT9837, User Manual

Page: 115 / 150

Calibration
115
Using the Manual Calibration Procedure
If you want to manually calibrate the analog input circuitry instead of auto-calibrating it, do
the following for each channel:
1. Select the A/D Calibration tab of the calibration utility.
2. Under the Calibration Settings area of the window, select the sampling frequency, in
Hertz, and the gain that you want to use.
Note: By default, this utility uses DC coupling with the current source disabled. This is
the recommended setting for most users. While changing these settings is not advised for
most users, users with unique applications can change these settings by clicking the
Advanced button.
3. Under the Manual Calibration area of the window, select the channel that you want to
calibrate, and then click the
Start button.
4. Adjust the offset as follows:
a. Verify that 0.000 V is applied to the channel that you want to calibrate.
The current voltage reading for this channel is displayed in the AD Value box.
b. Adjust the offset by entering values between 0 and 255 in the Offset edit box, or by
clicking the up/down buttons until the AD Value is 0.000 V.
5. Adjust the gain as follows:
a. Verify that +9.375 V is applied to the channel that you want to calibrate.
The current voltage reading for this channel is displayed in the AD Value box.
b. Adjust the gain by entering values between 0 and 255 in the Gain edit box, or by
clicking the up/down buttons until the AD Value is 9.3750 V.
6. Repeat these steps for each analog input channel on the module.
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.
Once you have finished this procedure, continue with “Calibrating the Analog Output
Subsystem.”