Enabling Duplicate Count Prevention In Ni-Daqmx; Synchronization Modes - National Instruments M Series User Manual

Enabling Duplicate Count Prevention in NI-DAQmx

You can enable duplicate count prevention in NI-DAQmx by setting the Enable Duplicate
Count Prevention attribute/property. For specific information about finding the Enable
Duplicate Count Prevention attribute/property, refer to the help file for the API you are using.

Synchronization Modes

The 32-bit counter counts up or down synchronously with the Source signal. The Gate signal and
other counter inputs are asynchronous to the Source signal. So M Series devices synchronize
these signals before presenting them to the internal counter.
M Series devices use one of three synchronization methods:
80 MHz Source Mode
•
Other Internal Source Mode
•
External Source Mode
•
In DAQmx, the device uses 80 MHz source mode if you perform the following:
• Perform a position measurement
• Select duplicate count prevention
Otherwise, the mode depends on the signal that drives Counter n Source. Table 7-8 describes the
conditions for each mode.
Table 7-8. Synchronization Mode Conditions
Duplicate Count
Prevention Enabled
Yes
No
No
No
No
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Type of Signal Driving
Measurement Counter n Source
Any Any
Position Any
Measurement
Any 80 MHz Timebase
All Except Position 20 MHz Timebase,
Measurement 100 kHz Timebase,
or PXI_CLK10
All Except Position Any Other Signal
Measurement (such as PFI or
RTSI)
M Series User Manual
Synchronization
Mode
80 MHz Source
80 MHz Source
80 MHz Source
Other Internal
Source
External Source
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