Siemens SIMATIC S7 Equipment Manual page 28

Data Communication with the PLC
Sensor-related
counter setting
4-6
The assigned counters for each sensor are set in one byte.
Table 4-3 shows the respective byte assigned.
Table 4-3 Bytes for setting the counters
Sensor Number
1
2
3
4
7
Byte (n+2)
Measuring cycle time
The measuring cycle time can be set in increments of 0.5 msec depending on
the sensor being used (length and required dead times). The maximum mea-
suring cycle time is 16 msec.
Starting the counter
When the counter is started with the sent START pulse, the maximum mea-
suring distance is reduced by the signal run time (approaching and returning
line) through all components. If the counter is started with the echo of the
START pulse, a synchronization error occurs.
Selecting the edge
Set the edge as described by the manufacturer of the sensor.
Byte
4
7
10
13
0
Measuring cycle time
0 0 0 0 0 16.0 msec
0 0 0 0 1 0.5 msec
0 0 0 1 0 1.0 msec
. .
. .
. .
1 1 1 1 1 15.5 msec
Starting the counter
0: Immediately with sent START pulse
1: With echo of the sent START pulse
Selecting the edge
Counter starts/stops with
0: Rising edge (L ® H)
1: Falling edge H ® L)
Resolution
0: 0.10 mm (max. meas. range of
approx. 6 m)
1: 0.05 mm (max. meas. range of
approx. 3 m)
SM 338 Equipment Manual
(4) J31069-D401-U1-A0-7618