©
National Instruments Corporation
11
6703/6704 Calibration Procedure
3.
Place the DMM in current mode.
4.
Run
AO_VWrite
with
chan
set to 16 and
voltage
set to 0.1. This will
cause the board to output 0.1 mA of current.
5.
Run
AO_VWrite
with the channel set to the current offset channel.
Adjust the
voltage
parameter until the DMM reads as close to 0.1 mA
as possible. The value you write to the current offset channel will be
close to 0.01 mA. Increasing the voltage value will lower the
magnitude of the current on current channel 16. Decreasing the voltage
value will increase the magnitude of the current on current channel 16.
6.
Run
AO_VWrite
with
chan
set to 16 and
voltage
set to 20.0. This will
cause the board to output 20.0 mA of current.
7.
Run
AO_VWrite
with the channel set to the current gain channel.
Adjust the
voltage
parameter until the DMM reads as close to 20.0 mA
as possible. The value you write to the current gain channel will be
close to 19.608 mA. Increasing the voltage value will lower the
magnitude of the current on current channel 16. Decreasing the voltage
value will increase the magnitude of the current on current channel 16.
You have now calibrated the current output.
Saving Calibration Values
Once you complete the calibration steps, you must store the new calibration
constants in the user calibration area of the board EEPROM to ensure that
your new calibration values are permanently saved and automatically
loaded when the board is powered on. If the calibration is being performed
by a metrology laboratory or another facility that maintains traceable
standards, the calibration values should also be stored in the factory
calibration area. This will protect the calibration constants by storing a
copy of them in a location that cannot be overwritten by the user. To access
the factory calibration area, you need the
ni6704Cal
.
dll
, available from
National Instruments.
To save the calibration constants and update the calibration dates, follow
these steps:
1.
Run
AO_Calibrate
with
operation
set to
2
and
calibrationArea
set
to
1
. This stores the new calibration constants in the user calibration
area of the board EEPROM.
Signal Name
Description
6704 Output
DMM Input
ICH16
Current Channel 16
Pin 67
High
AGND16
Analog Ground 16
Pin 68
Low
