Measurement Computing Data Translation DT3034, Руководство пользователя

Страница: 97 / 178

Chapter 6
96
Counter/Timer Features
The counter/timer circuitry on the board provides the clocking circuitry used by the A/D and
D/A subsystems as well as several user counter/timer features. This section describes the
following user counter/timer features:
• Units
• C/T clock sources
• Gate types
• Pulse types and duty cycles
• Counter/timer operation modes
Units
DT3034 boards support four user 16-bit counter/timer units (called counters); counters are
numbered 0, 1, 2, and 3.
Each counter accepts a clock input signal and gate input signal and outputs a clock output
signal (also called a pulse output signal), as shown in
Figure 28 .
Figure 28: Counter/Timer Channel
Each counter corresponds to a counter/timer (C/T) subsystem. To specify the counter to use
in software, specify the appropriate C/T subsystem. For example, counter 0 corresponds to
C/T subsystem element 0; counter 3 corresponds to C/T subsystem element 3.
C/T Clock Sources
The following clock sources are available for the user counters:
• Internal C/T clock
• External C/T clock
• Internally cascaded clock
Refer to the following subsections for more information on these clock sources.
Clock Input SIgnal
(internal, external, or
internally cascaded)
Counter
Gate Input Signal
(software or external
input)
Pulse Output Signal