Data Translation DT9834 Series, Руководство пользователя

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Principles of Operation
97
Counter/Timer Features
This section describes the following features of counter/timer (C/T) operations:
• C/T channels, described below
• C/T clock sources, described on page 98
• Gate types, described on page 98
• Pulse types and duty cycles, described on page 99
• C/T operation modes, described on page 99
C/T Channels
The DT9834 Series modules provide five 32-bit counter/timers. The counters are numbered 0,
1, 2, 3, and 4. Each counter accepts a clock input signal and gate input signal and outputs a
pulse (pulse output signal), as shown in
Figure 31 .
Figure 31: Counter/Timer Channel
To specify the counter/timer to use in software, specify the appropriate C/T subsystem. For
example, counter/timer 0 corresponds to C/T subsystem element 0; counter/timer 3
corresponds to C/T subsystem element 3.
Using software, you can also specify one or more of the counter/timers in the analog input
channel list. You need two channel list entries to read a 32-bit counter value. The first entry
stores the lower 16-bit word, and the second entry stores the upper 16-bit word.
If you need only the lower 16-bit word, you do not have to include the second entry. The entire
32-bit count value is latched when the lower 16-bit word is stored. This prevents the
counter/timer from incrementing between samples. Refer to
page 80 for more information
about using C/Ts in the channel list.
Clock Input SIgnal
(internal or external)
Counter
Gate Input Signal
(software or external
input)
Pulse Output Signal