Siemens SINUMERIK 840D sl Function Manual page 141

Activation via NC/PLC interface signals
Only protection zones that have been preactivated via the part program (see paragraph below
"Preactivation via part program") can be activated in the PLC user program via the NC/PLC
interface signals:
● DB21, ... DBX8.0 - 9.1 = 1 (activate machine-related protection zone 1 - 10)
● DB21, ... DBX10.0 - 11.1 = 1 (activate channel-specific protection zone 1 - 10)
For preactivation, see paragraph below "Preactivation via part program"
The activation of preactivated protection zones must be performed prior to the traversing
motion of the geometry axes. If the activation is performed during the traversing motion, these
protection zones are not taken into account in the current traversing motion. Reaction:
● Alarm "10704 Protection zone monitoring is not guaranteed"
● DB21, ... DBX39.0 = 1 (protection zone monitoring not guaranteed)
Note
The activation of preactivated protection zones must be performed prior to the traversing
motion of the geometry axes.
Automatic activation after the NC powers up
Protection zones that are to take effect immediately after the NC powers up can be specified
via the following system variables:
● Channel-specific protection zones:
$SC_PA_ACTIV_IMMED[<protection zone number>]
● Machine-specific protection zones:
$SN_PA_ACTIV_IMMED[<protection zone number>]
Note
With automatic activation, no relative offset of a protection zone is possible.
Note
A protection zone is only taken into account after the referencing of all geometry axes of
the channel in which it has been activated.
Preactivation via part program
Protection zones that are to be activated at a later time from the PLC user program must be
preactivated in the part program:
CPROT or NPROT (<protection zone number>, 1)
Basic Functions
Function Manual, 01/2015, 6FC5397-0BP40-5BA2
A3: Axis Monitoring, Protection Zones
3.3 Protection zones
141