Data Translation DT300 Series, Руководство по началу работы

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Chapter 5
60
Connecting Frequency Measurement Signals
This section describes two examples of how to connect frequency
measurement signals to the STP300 screw terminal panel.
The first configuration uses the same wiring as an event counting
application that does not use an external gate signal (see
Figure 17 on
page 58 ); the software uses the Windows timer to specify the duration
of the frequency measurement. In this configuration, the frequency of
the clock input is the number of counts divided by the duration of the
Windows timer.
If you need more accuracy than the Windows timer provides, you can
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
Figure
19 . In this configuration, the frequency of the clock input is the
number of counts divided by the period of the external gate input.
Figure 19: Connecting Frequency Measurement Signals
(Shown for Clock Input 0 and External Gate 0)
STP300 Panel
TB26
Signal Source TB29
TB28
Gate 0
TB31
User
Counter
Output 1
TB25
Digital Ground
User Clock Input 0