Enabling Duplicate Count Prevention In Ni-Daqmx; Synchronization Modes - National Instruments PCI-6281 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.
Duplicate Count
Prevention Enabled
Yes
No
No
No
No
Table 7-8. Synchronization Mode Conditions
Type of
Measurement
Any
Position
Measurement
Any
All Except Position
Measurement
All Except Position
Measurement
Signal Driving
Counter n Source
Any
Any
80 MHz Timebase
20 MHz Timebase,
100 kHz Timebase,
or PXI_CLK10
Any Other Signal
(such as PFI or
RTSI)
© National Instruments | 7-35
M Series User Manual
Synchronization
Mode
80 MHz Source
80 MHz Source
80 MHz Source
Other Internal
Source
External Source