Siemens SINUMERIK 840Di Function Manual page 113

Activation via PLC user program
A protection zone preactivated in the part program can be activated in the PLC user
program.
Preactivated protection zones
The NC indicates the preactivated protection zones:
DB21, ... DBX272.0 - 273.1 (machine-related protection zone 1 - 10 preactivated)
DB21, ... DBX274.0 -275.1 (channel-specific protection zone 1 - 10 preactivated)
Protection zone violation
Activated and preactivated protection zones that are or would be violated by the
programmed traversing motions of the current part program block if the PLC user program
would activate the preactivated protection zone:
DB21, ... DBX276.0 - DBX277.1 (machine-related protection zone 1 - 10 violated)
DB21, ... DBX278.0 - DBX279.1 (channel-specific protection zone 1 - 10 violated)
Activate
The preactivated protection zones can be activated from the PLC user program:
DB21, ... DBX8.0 to DBX9.1 (activate machine-related protection zone 1 - 10)
DB21, ... DBX10.0 to DBX11.1 (activate channel-specific protection range 1 - 10)
Deactivation
Protection zones activated from the part program cannot be deactivated by the PLC user
program.
Note
It follows from the rules listed above that protection zones that should be activated via the
PLC user program are intended specially for this. Preactivation in the part program is only
useful for these protection zones.
For protection zones that are known only in the part program and not in the PLC user
program, only activation in the part program makes sense.
Axis Monitoring, Protection Zones (A3)
Function Manual, 08/2005 Edition, 6FC5397-0BP10-0BA0
Detailed Description
2.4 Protection zones
2-41