204 Measurement Technique
imc CANSAS Users Manual - Doc. Version 1.9 - 05.12.2014© 2014 imc Meßsysteme GmbH
Example:
Counter frequency: 500 Hz , sampling interval: 5 ms, 100% corresponds to 159Nm
At a pulse duration of 250µs, the following values result:
250µs *5001/s*100%= 12,5%
Indicated value = 12,5% x 159Nm/100%= 19,86Nm
The result is updated every 5 ms.
Correct indication of the counter frequency is absolutely necessary for this procedure.
There is exactly one pulse time measurement per sampling interval. Change of the pulse times within
one sampling interval, called jitter, is not recognized. If you record the data with an imc device, you
can smooth the signal, averaging out the jitter by selecting the imc CANSAS channel’s sampling rate to
be as close as possible to the counter frequency. Then use Online FAMOS to smooth out the data
stream.
If the sampling interval is set to be faster than the counter frequency, the most recent result is
outputted repeatedly.
5.1.3.4 Mode (combined measurement)
Frequency
Frequency is determined by means of a combination measurement . If the frequency was
previously multiplied or divided, this can be reflected in the scaling value. The frequency is always
unsigned, for which reason there is no two-signal encoder for it.
Speed
The sequence of pulses is converted to m/s by means of a combination measurement . Toward this
end, the number of pulses per meter must be entered.
RPM
The sequence of pulses is converted to revolutions per minute by means of a combination
measurement . Toward this end, the number of pulses per revolution must be entered.
5.1.4 Digital Inputs
The switching thresholds can be toggled between TTL and 24 V range.
The switching thresholds are:
191
191
191
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