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XVME-500/590 Manual
February, 1988
Chapter 4
INPUT CALIBRATION
4 . 1 I N T R O D U C T I O N
Calibration facilities have been provided on the XVME-500/590 Analog Input Module
for the analog input circuits.
It is recommended that any time the module is
reconfigured (i.e. gain jumpers are changed, or new inputs are added etc.) that the
calibration should be checked and adjusted if necessary.
The calibration procedure entails offset and gain adjustment for the input channels
in either the unipolar or the bipolar modes of operation.
Table 4-l provides a list
of the potentiometers and their applications for the input circuit calibration.
Relative locations of the calibration potentiometers can be found in Figure 2-1
(XVME-500) or Figure 2-2 (XVME-590).
Table 4-1. A/D Calibration Potentiometers
Resistor
R2
R8
R9
R17
Rll
R13
Description
ADC unipolar offset adjust
ADC bipolar offset adjust
ADC gain adjust
Input offset adjust Prog. Gain (version 2 and 3 only)
Input Offset for Resis. Prog. Gain (version 1 only)
Gain Adjust for Resis. Prog. Gain (version 1 only)
4 2 .
INPUT CALIBRATION PROCEDURE
4.2.1
Equipment Required
The following equipment is required to perform input calibration:
1)
A 5-digit volt meter capable of reading
2)
A small flat-bladed screw driver.
3)
A precision voltage source, capable of supplying with a minimum
resolution of: 1.22mV.
The inputs can be calibrated in either the single-ended or differential configuration.
Calibration begins by offset nulling the instrumentation amplifier (either fixed gain
or programmable depending upon the version of the module) with channel 0 selected
and its inputs grounded.
4-l