Keithley KPCI-3101 Series, User Manual

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2-22 Principles of Operation KPCI-3101 — KPCI-3104 Series User’s Manual
Pulse outputs
The KPCI-3101–4 Series boards provide the following C/T pulse output signals:
• For Counter 0, the C/T output signal is screw terminal TB27 (pin 40 of connector J1)
•
For Counter 1, the C/T output signal is screw terminal TB31 (pin 6 of connector J1)
• For Counter 2, the C/T output signal is screw terminal TB35 (pin 37 of connector J1)
•
For Counter 3, the external C/T output signal is screw terminal TB39 (pin 3 of connector J1)
The KPCI-3101–4 Series board supports the following pulse output types on the clock output
signal:
•
High-to-low transitions — The low portion of the total pulse output period is the active por-
tion of the counter/timer clock output signal.
• Low-to-high transitions — The high portion of the total pulse output period is the active
portion of the counter/timer pulse output signal.
Using software, you can specify the duty cycle of the pulse. The duty cycle (or pulse width) indi-
cates the percentage of the total pulse output period that is active. A duty cycle of 50, then, indi-
cates that half of the total pulse is low and half of the total pulse output is high.
Figure 2-9
illustrates a low-to-high pulse with a duty cycle of approximately 30%.
Figure 2-9
Example of a Low-to-High pulse output type
Counter/Timer operation modes
The KPCI-3101–4 Series board supports the following counter/timer operation modes:
•
Event counting
• Frequency measurement
•
Rate generation
• One-shot
•
Repetitive one-shot
Refer to the following subsections for more information on these operation modes.
Total Pulse Period
Active Pulse Width
Low Pulse
High Pulse