Software Limit Switches - Siemens SIMATIC FM 353 Manual

Description of Functions
9.9

Software limit switches

Overview
To limit the working range, entries in the machine data (MD21 and MD22) specify
the start and stop limit switches. These limit switches are active at synchronization
of the axis.
If the limit switches are not needed, values lying outside the possible working
range should be entered in the machine data (MD21 and M22), or monitoring
should be switched off via the user program.
Warning
!
The software limit switches do not replace the hardware limit switches for EMER-
GENCY STOP responses.
Effect of software limit switches in modes
Jogging mode
At the limit switch the traveling movement is stopped in the limit-switch position,
and an error is signaled.
Control mode
If the actual value is beyond the end position, the traveling movement is stopped
and an error is signaled. The limit-switch position is overshot by the amount of the
necessary deceleration distance.
Reference-point approach mode
No effect.
Incremental relative, MDI, Automatic mode
Movement is stopped, or not even started, as soon as read-in of the set position
reveals that the position lies outside the working range. An error is signaled.
The following special cases exist:
S Continuous travel (−) for Set Actual Value On-the-Fly (G88, see Chapter 10).
S Continuous travel (+) for Set Actual Value On-the-Fly (G88, see Chapter 10).
Effect of software limit switches in tracking mode
If the actual value is beyond the end position, an error is signaled.
9-80
FM 353 Stepper Drive Positioning Module
6ES7 353-1AH01-8BG0