Limit-Switch Monitoring; Hardware Limit Switch - Siemens SINUMERIK 840D sl Function Manual

3.2.6

Limit-switch monitoring

Overview of the end stops and possible limit-switch monitoring:
3.2.6.1

Hardware limit switch

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, ... DBX12.0/1 = 1 (hardware limit switch minus/plus)
Parameterization
The braking behavior of the machine axis upon reaching the hardware limit switch is
configurable via the machine data:
MD36600 $MA_BRAKE_MODE_CHOICE (braking behavior on hardware limit switch)
Value
0
1
Effectiveness
The hardware limit-switch monitoring is active after the controller has ramped up in all modes.
Basic Functions
Function Manual, 01/2015, 6FC5397-0BP40-5BA2
Meaning
Braking with the configured axial acceleration
Rapid stop (set velocity = 0)
A3: Axis Monitoring, Protection Zones
3.2 Axis monitoring functions
103