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National Instruments Corporation
5
AO Waveform Calibration Procedure for NI-DAQmx
•
One of the following DAQ accessories:
–
SCB-68—The SCB-68 is a shielded I/O connector block with
68 screw terminals for easy signal connection to 68- or 100-pin
DAQ devices.
–
CB-68LP/CB-68LPR/TBX-68—The CB-68LP, CB-68LPR, and
TBX-68 are low-cost termination accessories with 68 screw
terminals for easy connection of field I/O signals to 68-pin DAQ
devices.
Test Considerations
Follow these guidelines to optimize connections and test conditions during
calibration:
•
Keep connections to the NI 671
X
/672
X
/673
X
short. Long cables and
wires act as antennae, picking up extra noise, which can affect
measurements.
•
Use shielded copper wire for all cable connections to the device.
•
Use twisted-pair wire to eliminate noise and thermal offsets.
•
Maintain a temperature between 18 and 28 °C. To operate the module
at a specific temperature outside this range, calibrate the device at that
temperature.
•
Keep relative humidity below 80%.
•
Allow a warm-up time of at least 15 minutes to ensure that the
measurement circuitry is at a stable operating temperature.
Calibration Process
This section provides instructions for verifying and calibrating your device.
Calibration Process Overview
The calibration process has four steps:
1.
Initial Setup—Configure your device in NI-DAQmx.
2.
AO Verification Procedure—Verify the existing operation of the
device. This step allows you to confirm that the device was operating
within its specified range prior to calibration.
3.
AO Adjustment Procedure—Perform an external calibration that
adjusts the device calibration constants with respect to a known voltage
source.
4.
Perform another verification to ensure that the device is operating
within its specifications after adjustment.
