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National Instruments Corporation
9
6703/6704 Calibration Procedure
7.
Again, compare the resulting value shown by the DMM to the upper
and lower limits listed in
section table. If the value falls
between these limits, the board passes current verification.
8.
Disconnect the DMM from the 6704.
You have now verified the current output of your board.
Calibrating Your Board
The 6703/6704 calibration procedure allows you to adjust the output
calibration constants. At the end of each calibration procedure, these new
constants will be stored in the user calibration area, ensuring that the board
stores a permanent record of the calibration constants. Storing the
calibration constants here also ensures that the constants automatically load
when the board is powered up.
Calibrating Voltage Output
For the voltage outputs, you need to make offset and gain adjustments. You
perform offset adjustment first, followed by gain adjustment. You will then
perform both offset and gain adjustment again to ensure proper accuracy.
This second set of offset and gain adjustments is necessary because a large
initial change in one of the calibration channels can affect the accuracy of
the other calibration channel. The following table lists the offset and gain
channel numbers.
You need a DMM to measure the voltage outputs. Make sure that you have
read the
Equipment and Other Test Requirements
section listed above, and
follow these steps:
1.
Run
Set_DAQ_Device_Info
with
infoType
set to
ND_CALIBRATION_ENABLE
and
infoValue
set to
ND_YES
. This step
configures the board so you can access the calibration channels.
2.
Connect the DMM to the board as shown in the following table.
Calibration
Channel
6703 Channel
Numbers
6704 Channel
Numbers
Voltage Offset
16
32
Voltage Gain
17
34
Signal Name
Description
6703/6704
Output
DMM Input
VCH0
Voltage Channel 0
34
High
AGND0
Analog Ground 0
68
Low
