Detailed Description   
2.3 Monitoring of static limits 
  Axis Monitoring, Protection Zones (A3) 
2-22  Function Manual, 08/2005 Edition, 6FC5397-0BP10-0BA0 
2.3  2.3 Monitoring of static limits 
2.3.1  Overview of the limit switch monitoring 
Overview of possible limit switch monitoring functions: 
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Fig. 2-8  Travel limits 
2.3.2  Hardware limit switches 
Function 
A hardware limit switch is normally installed at the end of the traversing range of a machine 
axis. It serves to protect against accidental overtravelling of the maximum traversing range of 
the machine axis while the machine axis is not yet referenced. 
If the hardware limit switch is triggered, the PLC user program created by the machine 
manufacturer sets the corresponding interface signal: 
DB31, ... DBX12.0 / 12.1 = 1 (hardware limit switch minus / plus)