Keithley KPCI-3110, User Manual

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2-28 Functional Description KPCI-3110 and KPCI-3116 User’s Manual
Frequency measurement
Use frequency measurement mode to measure the frequency of the signal from counter’s associ-
ated clock input source over a specified duration. In this mode, use an external C/T clock source;
refer to
page 2-23 for more information on the external C/T clock source.
One way to perform a frequency measurement is to use the same wiring as an event counting
application that does not use an external gate signal, as shown in
Figure 2-13 .
Figure 2-13
Connecting frequency measurement signals without an external gate input
(shown for Clock Input 0)
In this configuration, use software to specify the counter/timer mode as frequency measurement
or event counting, and the duration of the Windows timer over which to measure the frequency.
(The Windows timer uses a resolution of 1ms.) In this configuration, frequency is determined
using the following equation:
STP-3110 Panel
TB58
Signal Source
Digital Ground
User Clock Input 0
TB83
TB61
TB60
TB108
Digital Shield
Frequency Measurement
Number of Events
Duration of the Windows Timer
---------------------------------------------------------------------------- =