IO/Inputs/[DIN]/Count/SampleTime Registry Key
NAME
IO/Inputs/[DIN]/Count/SampleTime
DEFAULT
0.0 (seconds)
DESCRIPTION
This defines a sampling period in seconds. A fractional value may be
specified.
Normally Counts accumulate until reset separately by the user threw the
WebUI, JRMON or other application. This is the case when SampleTime is
set to 0.0 (default). When a nonzero time is defined the counter displays
the total count accumulated during that period. For instance, with the
appropriate combination of Multiplier and SampleTime the counter can
display Revolutions Per Minute (RPM) for a input using a Hall Effect
sensor mounted on a wheel hub.
NOTES
When RPM is measured in this fashion it is perhaps better to allow an
application to perform the calculation. With access to the I/O log and
the appropriate Java class the application can average pulses over a
moving window or sample time for the accurate real-time measurement of
high RPMs. When the wheel is rotating extremely slowly the application can
then use the pulse-to-pulse timing to derive an estimate of fractional RPMs
and even the rate of change. This would be a useful approach for use with
a wind turbine as an example.
SEE ALSO
HELP Topics:
JRMON,
COUNTING,
DIN
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