Measurement Computing Data Translation DT3034 User Manual page 103

Chapter 6
Frequency Measurement
Use frequency measurement mode to measure the frequency of the signal from counter's
associated clock input source over a specified duration. In this mode, use an external C/T
clock source; refer to
Connect a pulse of a known duration (such as a one-shot output of another user counter) to
the external gate input, as shown in
Signal Source
In this configuration, use software to set up the counter/timers as follows:
1. Set up one of the counter/timers for one-shot mode, specifying the clock source, clock
2. Set up the counter/timer that will measure the frequency for event counting mode,
3. Start both counters (events are not counted until the active period of the one-shot pulse is
4. Read the number of events counted. (Allow enough time to ensure that the active period
5. Determine the measurement period using the following equation:
6. Determine the frequency of the clock input signal using the following equation:
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Digital Ground
Figure 32: Connecting Frequency Measurement Signals
(Shown for Clock Input 0 and External Gate 0)
frequency, gate type, and type of output pulse (high or low).
specifying the clock source to count, and the gate type (this should match the pulse
output type of the counter/timer set up for one-shot mode).
generated).
of the one-shot occurred and that events have been counted.)
Measurement period =
Frequency Measurement =
for more information on the external C/T clock source.
Figure 32.
User Clock Input 0
Gate 0
TB83
1 * Active Pulse Width
Clock Frequency
Number of Events
Measurement Period
DT740 Screw
Terminal Panel
TB58
TB60
TB61
User
TB63
Counter
Output 1