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Chapter 2 Function Reference — SCXI_Calibrate_Setup
NI-DAQ FRM for PC Compatibles 2-330
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National Instruments Corporation
SCXI_Calibrate_Setup
Format
status = SCXI_Calibrate_Setup (SCXIchassisID, moduleSlot, calOp)
Purpose
Used to ground the amplifier inputs of an SCXI-1100, SCXI-1122, or SCXI-1141 so that you
can determine the amplifier offset. You can also use this function to switch a shunt resistor
across your bridge circuit to test the circuit. Shunt calibration is supported for the SCXI-1122
or SCXI-1121 modules with the SCXI-1321 terminal block.
Parameters
Input
Parameter Discussion
calOp indicates the calibration mode you want.
0: Disable calibration.
1: Connect the positive and negative inputs of the SCXI-1100, SCXI-1122,
or SCXI-1141 amplifier together and to analog reference.
2: Switch the shunt resistors across the bridge circuit on the SCXI-1121
(Revision C or later) or SCXI-1122.
Using This Function
The zero offset of the SCXI-1100, SCXI-1122, or SCXI-1141 amplifiers varies with the
module gain. When you know the offset at a specific gain setting, you can add that offset to
any readings acquired at that gain. In general, the procedure for determining the offset at a
particular gain is as follows:
1.
SCXI_Single_Chan_Setup—Enable the module output, route the module output
on the SCXIbus if necessary, and resolve any SCXIbus contention if necessary. For
the SCXI-1100 and SCXI-1122, the module channel you specify is irrelevant.
2.
SCXI_Set_Gain—Set the module gain to the setting that you will use in your
application.
3.
SCXI_Calibrate_Setup—Ground the amplifier inputs.
Name Type Description
SCXIchassisID i16 logical ID assigned to the SCXI chassis
moduleSlot i16 chassis slot number
calOp i16 calibration mode