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National Instruments Corporation
13
SCXI-1122 Calibration Procedure
12. Convert the DMM voltage reading to a binary reading by using one
of the following equations:
For example, using a 12-bit product, such as a PCI-MIO-16E-1, and
obtaining a DMM reading of 9.9 V, you would have the following
equation:
Repeat steps 5 through 12 for the remaining input ranges.
When you are finished, you have a table of calibrator voltages and the
corresponding binary readings.
You have now finished adjusting the offset and gain errors on the
SCXI-1122 module.
Adjusting Calibration Constants
Complete the following steps to adjust the calibration constants:
1.
Call
SCXI_Cal_Constants
to create and store the new calibration
constants in the memory of the SCXI-1122 module. Call this function
for each gain setting. Set the following parameters:
•
SCXIchassisID
—The ID assigned by MAX
•
ModuleSlot
—1, unless you have installed the module in a
different slot
•
channel
— –1
•
opCode
—2
•
calibrationArea
—0
•
rangeCode
—0 (not used for the SCXI-1122 module)
•
SCXIgain
—The appropriate gain for the pair of constants you are
about to save on the SCXI-1122 module
•
DAQboard
—Device number assigned by MAX
•
DAQChan
—0
•
DAQGain
—1 for 16-bit devices, –1 for 12-bit devices
•
Tbgain
—1
binary reading for 12-bit products
DMM voltage gain
×
20
----------------------------------------------------
2
12
×
=
binary reading for 16-bit products
DMM voltage gain
×
20
----------------------------------------------------
2
16
×
=
binary reading
9.9 20
⁄
(
)
2
12
×
2027.52
=
=
