Siemens SIMATIC FM 452 Manual page 114

Settings
Sequence of the Settings
Depending on the type of measurement, the FM 452 updates the data on the
module at different times. The FM 452 signals every update in a parameter on the
return interface.
Length Measurement
MSR_ON
I1
Update data
MSR_DONE
1. Set the function switch for "length
measurement".
2. The rising edge of input I1 starts the length
measurement.
3. The falling edge of input I1 terminates a
measurement in progress. The FM 452 updates
the data start value, end value, and length.
4. With the MSR_DONE parameter set, the
FM 452 signals the updating of the data. The
parameter indicates that the measurement is
completed. The results of the measurement can
be read out.
5. The start of another measurement with the
rising edge of I1 resets the MSR_DONE
parameter.
If the setting is switched off during a length
measurement, the FM 452 does not update the
data. The MSR_DONE parameter remains reset.
9-16
Edge Detection
EDGE_ON
I1
Update data
MSR_DONE
1. If necessary, enter a value for the minimum
edge-to-edge distance in the parameter DB.
Write and activate the machine data.
2. Set the function switch for "edge detection". The
MSR_DONE parameter is set.
3. The rising edge of input I1 starts the edge
acquisition. The results of the measurement are
updated and can be read out, the start of the
measurement is entered; the end value and
length become -1.
4. After the update, the FM 452 signals the
change by resetting the MSR_DONE
parameter.
5. The falling edge of input I1 terminates a
measurement in progress. The FM 452 updates
the data for end value of the measurement and
length.
6. After updating, the FM 452 signals the change
by setting the MSR_DONE parameter. The
results of the measurement can be read out.
7. The start of another measurement with the
rising edge of I1 resets the MSR_DONE
parameter.
If the setting is switched off during edge acquisition,
the FM 452 does not update the data. The
MSR_DONE parameter remains reset.
FM 452 Electronic Cam Controller
C79000-G7076-C452-04