Measurement Computing Data Translation DT3010 Series, Руководство пользователя, Страница: 84 / 232

Wiring Signals
83
Figure 42: Cascading Counters on an STP268-EC Screw Terminal Panel
(Shown for Event Counting Using Counters 0 and 1 and External Gate 0)
Connecting Frequency Measurement Signals
You can connect a frequency measurement application to a DT740 or STP268 screw terminal
panel in two ways.
The first configuration uses the same wiring as an event counting application that does not
use an external gate signal (see
Figure 35 on page 78 for the DT740, Figure 38 on page 80 for
the STP268, or Figure 41 on page 82 for the STP268-EC). 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.
In this configuration, the frequency of the clock input is the number of counts divided by the
period of the external gate input. For an example of this configuration, refer to
Figure 43 for
the DT740, Figure 44 for the STP268, or Figure 45 for the STP268-EC.
TB5
STP268-EC Panel
TB4
TB37
TB35
Signal
Source
User Clock Input 0
Digital Ground
Gate 0
External
Gating
Switch
Gate 1
Note that you can internally cascade counters using software; if you
internally cascade the counters, you do not have to make the
external cascading connections. Note also that this example shows
the use of an external gate; however, this connection is not required.
Digital Ground
TB36
TB38
TB3
User
Clock
Input 1
User
Clock
Output 0