Siemens S7-300 - Special Tracks

Cam control basics
3.2 Tracks and track result
FM 352 electronic cam controller
20 Operating Instructions, 05/2011, A5E01071724-03
3.2.2 Special tracks
Definition
You can program tracks 0 to 2 for operation as special tracks:
● Track 0 or 1: Counter cam track
● Track 2: Brake cam track
Input I0 must be evaluated in order to enable the track.
Requirements
Requirements of working with special tracks:
● You programmed the cams for the track
● Cam processing is enabled
● The corresponding track is enabled
● The track is programmed as special track
Counter cam track
A counter cam track counts the status transitions of the track results on this track.
Define a counter value, and then start the counter function.
The counter value of the relevant track decrements by the count of 1 at each positive edge of
the track result signal.
The track flag bit = 0 as long as the value of the counter cam track is not equal to zero.
When the counter value = 0, the controller sets the track flag bit and, if programmed
accordingly, the track signal (see chapter "Interfaces of the cam controller (Page 25)").
It resets the track flag bit, and set
s the default value of the counter at the next negative edge
of the track
result signal (all cams on this track are disabled).
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Figure 3-2 Setting a counter cam track