National Instruments NI 6738, Процедура калибровки, Страница: 24 / 28

NI 6738/6739 Calibration Procedure | © National Instruments | 23
Complete the following steps to perform checks on the counter of your device.
1. Connect your counter positive input to CTR 0 OUT/PFI 7/P1.7 (Connector 0, pin 9) and
your counter negative input to D GND PFI 6/7 (Connector 0, pin 42).
2. Create a task using
DAQmxCreateTask
.
3. To verify the Counter 0, call
DAQmxCreateCOPulseChanFreq
with the following
parameters:
Note Throughout the procedure, refer to the NI-DAQmx function call parameters
for the LabVIEW input values.
• taskHandle :
taskHandle
• counter :
Dev_name/ctr0
• nameToAssignToChannel :
CounterOutputChannel
• units :
DAQmx_Val_Hz
• idleState :
DAQmx_Val_Low
• initialDelay :
0.0
• freq :
5000000.0
• dutyCycle :
0.5
4. Call
DAQmxCfgImplicitTiming
with the following parameters:
• taskHandle :
taskHandle
• sampleMode :
DAQmx_Val_ContSamps
• sampsPerChan :
10000
5. Call
DAQmxStartTask
with the following parameter:
• taskHandle :
taskHandle
The DAQ device generates a 5 MHz square wave.
6. Configure the external counter to measure frequency, 1 M
Ω
impedance, and gate time to
achieve the minimum accuracy requirements from Table 1.
7. Take a measurement of the square wave using the external counter.
8. Compare the value read by your counter to the test limits shown on the device table in the
Test Limits section. If the value falls between these limits, the device passes the test.
9. Call
DAQmxStopTask
with the following parameter:
• taskHandle :
taskHandle
10. Call
DAQmxClearTask
with the following parameter:
•
taskHandle
:
taskHandle
11. Disconnect the external counter from your device.
Note If the counter verification procedure determines that the device is outside of
the limits, refer to the Worldwide Support and Services section for assistance in
returning the device to NI.