Data Translation DT9800 Series, Руководство пользователя

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Chapter 2
56
6. Determine the frequency of the clock input signal using the
following equation:
Frequency Measurement = Number of Events
Measurement Period
Figure 8 shows an example of a frequency measurement operation. In
this example, three events are counted during a duration of 300 ms.
The frequency, then, is 10 Hz, since 10 Hz = 3/(.3 s).
Figure 8: Example of Frequency Measurement
Rate Generation
Use rate generation mode to generate a continuous pulse output
signal from the counter; this mode is sometimes referred to as
continuous pulse output or pulse train output. You can use this pulse
output signal as an external clock to pace other operations, such as
analog input or other counter/timer operations.
While the pulse output operation is enabled, the counter outputs a
pulse of the specified type and frequency continuously. As soon as
the operation is disabled, rate generation stops.
External C/T
Clock
Input Signal
frequency measurement
starts
frequency
measurement stops
Duration over which the
frequency is measured = 300 ms
3 Events Counted