Siemens SINUMERIK 840D sl Programming Manual page 251

Status after booting
Protection zones can be activated straight after booting and subsequent reference point
approach. The system variable $SN_PA_ACTIV_IMMED[<n>] or
$SC_PA_ACTIV_IMMED[<n>] must be set to TRUE for this purpose. They are always
activated with Status = 2 and have no offset.
Multiple activation of protection zones
A protection zone can be active simultaneously in several channels (e.g. tailstock where
there are two opposite sides). The protection zones are only monitored if all geometry axes
have been referenced.
The following applies:
● The protection zone cannot be activated simultaneously with different offsets in a single
● Machine-oriented protection zones must have the same orientation on both channels.
Job Planning
Programming Manual, 06/2009, 6FC5398-2BP20-0BA0
channel.
3.2 Activating/deactivating protection zones (CPROT, NPROT)
Protection zones
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