Software Limit Switch - Siemens SINUMERIK 840D sl Function Manual

A3: Axis Monitoring, Protection Zones
3.2 Axis monitoring functions
Effect
Upon reaching the hardware limit switch, the following occurs:
● Alarm 21614 "Channel <Channel number> Axis <Axis name> Hardware limit switch
<Direction>"
● The machine axis is braked according to the configured braking behavior.
● If the axis/spindle is involved in interpolation with other axes/spindles, these are also braked
according to their configured braking behavior.
● The traversing keys of the affected machine axis are blocked based on the direction.
3.2.6.2

Software limit switch

Function
Software limit switches serve to limit the traversing range of a machine axis. Per machine axis
and per traversing direction, two (1st and 2nd) software limit switches are available:
MD36100 POS_LIMIT_MINUS (1st software limit switch minus)
MD36110 POS_LIMIT_PLUS (1st software limit switch plus)
MD36120 POS_LIMIT_MINUS2 (2nd software limit switch minus)
MD36130 POS_LIMIT_PLUS2 (2nd software limit switch plus)
By default, the 1st software limit switch is active. The 2nd software limit switch can be activated
for a specific direction with the PLC user program:
DB31, ... DBX12.2 / 12.3 (2nd software limit switch minus/plus)
Effectiveness
The software limit switches are active:
● Immediately after the successful referencing of the machine axis.
● In all operating modes.
Boundary conditions
● The software limit switches refer to the machine coordinate system.
● The software limit switches must be inside the range of the hardware limit switches.
● The machine axis can be moved to the position of the active software limit switch.
● PRESET
After use of the function PRESET, the software limit-switch monitoring is no longer active.
The machine must first be re-referenced.
● Endlessly rotating rotary axes
No software limit-switch monitoring takes place for endlessly rotating rotary axes:
MD30310 $MA_ROT_IS_MODULO == 1 (modulo conversion for rotary axis and spindle)
Exception: Setup-rotary axes
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Function Manual, 01/2015, 6FC5397-0BP40-5BA2
Basic Functions