National Instruments DAQ Series, Руководство пользователя

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Chapter 3 Connecting Signals
DAQCard-700 User Manual 3-16 ni.com
General-Purpose Counter and Timing Signal
Connections
The general-purpose timing signals include the GATE, CLK, and OUT
signals for the three integrated counter/timers, except CLK of counter 0
is not available on the I/O connector. You can use the counter/timers for
general-purpose applications such as pulse and square wave generation,
event counting, and pulse-width, time-lapse, and frequency measurement.
For these applications, CLK and GATE signals are sent to the counters, and
the counters are programmed for various operations. The only exceptions
are counter 0, which has an internal 1 MHz clock, and counter 1, which can
also be configured to use this clock.
The MSM82C54 is described briefly in the Timing I/O Circuitry section of
Chapter 4, Theory of Operation .
To perform pulse and square wave generation, program a counter to
generate a timing signal at its OUT output pin.
To count events, program a counter to count rising or falling edges applied
to any of the MSM82C54 CLK inputs. You can then read the counter value
to determine the number of edges that have occurred. You can gate counter
operation on and off during event counting. Figure 3-8 shows connections
for a typical event-counting operation in which a switch is used to gate the
counter on and off.