Data Translation DT3000 Series, Руководство пользователя, Страница: 86 / 156

Principles of Operation
85
• Rising-edge external gate input – Triggers a counter/timer operation on the transition
from the low level to the high level (rising edge). In software, this is called a high-edge
gate type. Note that this gate type is used only for one-shot and repetitive one-shot mode;
refer to
page 86 for more information on these modes.
Specify the gate type in software. Connect the external gate signal to TB5 of the DT730 or
DT730-T screw terminal panel (pin 5 of connector J1 on the DT3000 Series board).
Pulse Output Signals and Duty Cycles
DT3000 Series boards provide one pulse output signal. The pulse signal is output on TB3 of
the DT730 and DT730-T screw terminal panel (pin 3 of connector J1 on the DT3000 Series
board).
DT3000 Series boards support high-to-low pulse output signals only. With a high-to-low
transition, the low portion of the total pulse output period is the active portion of the
counter/timer clock output signal.
The duty cycle (or pulse width) indicates the percentage of the total pulse output period that is
active. For example, a duty cycle of 50 indicates that half of the total pulse is low and half of
the total pulse output is high.
Figure 23 illustrates a high-to-low pulse with a duty cycle of
approximately 50%.
Note: For rate generation mode, the duty cycle must be 50 or 100 only. For one-shot and
repetitive one-shot mode, the duty cycle must be 100.
Figure 23: Example of a High-to-Low Pulse Output Signal
Total Pulse Period
Active Pulse Width
low pulse
high pulse
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com