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Chapter 6
Counters
Counter
n
Internal Output and Counter
n
TC Signals
The Counter
n
Internal Output signal changes in response to Counter
n
TC.
The two software-selectable output options are pulse output on TC and toggle output on TC. The
output polarity is software-selectable for both options.
With pulse or pulse train generation tasks, the counter drives the pulse(s) on the Counter
n
Internal Output signal. The Counter
n
Internal Output signal can be internally routed to be a
counter/timer input or an “external” source for AI, AO, DI, or DO timing signals.
Routing Counter
n
Internal Output to an Output Terminal
You can route Counter
n
Internal Output to any PFI terminal.
Frequency Output Signal
The Frequency Output (FREQ OUT) signal is the output of the frequency output generator.
Routing Frequency Output to a Terminal
You can route Frequency Output to any PFI terminal.
Default Counter/Timer Routing
Counter/timer signals are available to parallel digital I/O C Series modules. To determine the
signal routing options for modules installed in your system, refer to the
Device Routes
tab
in MAX.
You can use these defaults or select other sources and destinations for the counter/timer
signals in NI-DAQmx. Refer to
Connecting Counter Signals
in the
NI-DAQmx Help
or the
LabVIEW Help
for more information about how to connect your signals for common counter
measurements and generations. Refer to
Physical Channels
in the
NI-DAQmx Help
or the
LabVIEW Help
for a list of default PFI lines for counter functions.
Other Counter Features
The following sections list the other counter features available on the cDAQ chassis.
Cascading Counters
You can internally route the Counter n Internal Output and Counter n TC signals of each counter
to the Gate inputs of the other counter. By cascading two counters together, you can effectively
create a 64-bit counter. By cascading counters, you also can enable other applications. For
example, to improve the accuracy of frequency measurements, use reciprocal frequency
measurement, as described in the
Large Range of Frequencies with Two Counters
section.
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