Measurement Computing Data Translation DT3034, Руководство пользователя

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Principles of Operation
107
Repetitive One-Shot
Use repetitive one-shot mode to generate a pulse output signal each time the board detects a
trigger (determined by the gate input signal). You can use this mode to clean up a poor clock
input signal by changing its pulse width, then outputting it.
In repetitive one-shot mode, the internal C/T clock source is more useful than an external C/T
clock source; refer to
page 96 for more information on the internal C/T clock source.
Use software to specify the counter/timer mode as repetitive one-shot, the polarity of the
output pulses (high-to-low transitions or low-to-high transitions), the C/T clock source, and
the gate type to trigger the operation. Refer to
page 99 for more information on pulse output
types and to page 98 for more information on gates.
Note: In the case of a repetitive one-shot operation, the pulse width is set to 100%
automatically.
Triggers that occur while the pulse is being output are not detected by the board.
When the one-shot operation is triggered (determined by the gate input signal), a pulse is
output. When the board detects the next trigger, another pulse is output. This operation
continues until you stop the operation.
Figure 39 shows an example of a repetitive one-shot operation using the DT740 screw terminal
panel, an external gate (rising edge), a clock output frequency of 1 kHz (one pulse every 1 ms),
and a low-to-high pulse type.
Figure 39: Example of Repetitive One-Shot Mode
Pulse
Output
Signal
External
Gate
Signal
100% duty cycle
Repetitive One-Shot
Operation Starts
1 ms period
100% duty cycle
100% duty
cycle
1 ms period