Siemens SINUMERIK 828D Function Manual page 122

A3: Axis Monitoring, Protection Zones
2.3 Protection zones
Enabling of workpiece-related protection zones
When a workpiece-related protection zone has been violated, the operator can enable it temporarily with NC start
in the AUTOMATIC and JOG modes so that it can be traversed. This clears the alarm and travels into the
protection zone in the AUTOMATIC and MDI operating modes.
Only workpiece­related protection zones can be enabled temporarily with NC start and traversed by all
tool­related protection zones including the programmed path.
If on NC-START the preactivated tool or workpiece­related protection zone is deactivated by the PLC after the
alarm, machining is continued without the protection zone being enabled temporarily.
If a fully operative, preactivated protection zone causes a machining interruption and the output of an alarm
owing to protection-zone violation, machining can be resumed on NC start if the PLC makes the zone inoperative
again.
If enabling of a protection zone is to be safeguarded better than with a simple NC start, NC start must be disabled
or made dependent on other conditions in the PLC user program when this alarm is triggered.
If the user does not want to permit overrunning the protection zone, he can terminate the traversing movement
with NC RESET.
If several protection zones are violated at the same time by the movement, acknowledgment is required for each
of these protection zones. With NC start the individual protection zones can then be enabled one after the other.
Application for temporary enabling:
Drilling a turned part: The drill is allowed to enter the protection zone of the spindle chuck.
Monitoring of overlaid motion
On preparation of the NC blocks, part of the offsets of geometry axes resulting from the overlaid motions are
taken into account.
If further offsets occur that could not be taken into account on preparation of the blocks, the channel­specific PLC
interface signal is set.
DB31, ... DBX39.0 (protection-zone monitoring not guaranteed).
This signal is set while offsets are active that cannot be taken into account. The signal can be set and reset within
a block.
Simultaneously with the PLC interface signal, a self­canceling alarm 10704 "Protection-zone monitoring is not
guaranteed" is output.
The following overlaid motions of geometry axes are taken into account in the preparation of blocks:
1. DRF offsets
2. Work offsets external
3. Fine tool offsets
4. Rapid retraction
5. Offsets generated by compile cycles
6. Oscillation
7. Concurrent positioning axes
8. Positioning axes
Basic Functions
122
Function Manual, 09/2011, 6FC5397-0BP40-2BA0