Reading Twf Data - Allen-Bradley 1444-TSCX02-02RB User Manual

Appendix A CIP Objects
332

Reading TWF Data

Processing the returned data into the TWF is merely a matter of determining
the period, RPM, and number of samples (if synchronous) of the data. The
data values themselves are returned as floating point values that need no further
processing. The following describes how to calculate the period of the TWF.
Asynchronous Measurements
Calculate the time waveform period:
Synchronous Measurements
Calculate the number of samples:
Read the Samples per Revolution (SamplesPerRev):
Samples per Revolution is returned in the first bye of the
SamplePeriodInSec value
Read the RPM in Hz (RPM
RPM in Hz is returned in the last three bytes of the SamplePeriodInSec
value
Calculate the time waveform period:
Rockwell Automation Publication 1444-UM001D-EN-P - June 2018
SamplePeriodInSec * ByteCount
TWF Period (sec) =
NumSamples=
Hz
):
TWF Period (sec) =
RPM
4
ByteCount
4
NumSamples
Hz
* SamplesPerRev