C.1.2 Analog Input Calibration Procedure
Calibrating the analog input section requires adjusting the input offset voltage, the ± 10V range,
±5V range, and the 0 to 10V range. The procedures are listed separately, but should be performed during a single calibration session.
Note: The input offset voltage must be adjusted and in specified limits before the other adjustments are performed.
Adjust Input Offset Voltage
1.Attach the termination panel to
2.Ground analog input channel 0 to analog ground, not digital ground, on the termination panel.
3.Connect a precision voltmeter between TP27 and analog ground, TP21.
4.Run a program, such as SYSCHECK, to configure the UDAS for
5.Read the voltage from the voltmeter.
6.Reconfigure the UDAS for a gain of 100. Adjust R58 so that the offset voltage read from the voltmeter is equal to the voltage read in step 4.
7.Repeat steps 4 and 5 to minimize the offset difference observed between the two gain settings.
The offset difference observed between the two gain settings should be within ±0.5 mV. If pos- sible, try to achieve less than ±0.2 mV offset difference.
8.Reconfigure the UDAS to a gain of 10 and verify the offset value is less than 0.5 mV different from the last value read at a gain of 1.
Adjust Offset and Gain for ±10Volt Input Range
1.Verify the termination panel is attached to the
2.Attach a voltage calibrator to channel 0 with all of the other channels grounded.
3.Run a program, such as SYSCHECK, to configure the UDAS for a range of ±10 V and gain of 1.
4.Set the calibrated input to 0 V, or short channel 0 to analog ground.
5.Set SYSCHECK or other program to average 50 readings. Manually or automatically take readings repeatedly.
6.Adjust Pot R51 until the software displays 0 V.
