Siemens S7-300 - 1.3 Guide to commissioning fail-safe signal modules

Cam control basics
3.1 Properties of the cam types
FM 352 electronic cam controller
Operating Instructions, 05/2011, A5E01071724-03
17
Inverse cam
An inverse cam comes about if the cam start is greater than the cam end. The following table
shows the effect of an inverse cam with a linear axis and a rotary axis.
Inverse cam with a linear axis Inverse cam with a rotary axis
1( 1$
1(
1$

The cam start (NA) is greater than the cam end
(NE).
The cam start (NA) is more positive than the cam
end (NE).
With both types of axes there must always be an interval of at least 4 pulses between the cam start
and the cam end.