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Siemens SINUMERIK Controller
Program/G-code · Intermediate · 30-120 minutes
Siemens 26236 - Block : Protection area element , referred to in $NP_NEXT[ ], is
This alarm occurs when a protection area element references the protection area it belongs to, creating a closed definition chain. Fix by correcting the protection area definition in the program.
26236
Siemens 26236 - Block : Protection area element , referred to in $NP_NEXT[ ], is
Block: Protection area element, referred to in $NP_NEXT, is
A closed definition chain was found, i.e. a protection area element contains the protection area of which it is a part Control reaction: Correction block is reorganized. Interface signals are set. Alarm display.
Root Cause Summary
This alarm occurs when a protection area element references the protection area it belongs to, creating a closed definition chain. Fix by correcting the protection area definition in the program.
Safety
- Only qualified personnel should diagnose and clear control alarms; follow the machine builder's safety procedures and lockout/tagout where hardware work is required.
Causes and Fixes
- 1
Locate the block
Check the channel and block number in the alarm message to find the problematic code.
- 2
Review protection area
Inspect the protection area definition for self-referencing elements and correct the logic or reference.
- 3
Test the program
Clear the alarm and run a simulation or dry run to verify the fix.
Call a technician if:
- ·If the alarm persists after verifying and correcting the protection area definition
- ·If the program logic appears correct but the error remains
Prevention
- Always validate protection area definitions during programming
- Use simulation to detect logical errors before running on actual machine
- Verify protection zones do not conflict with required tool paths
- Document protection area logic for future reference
Common Mistakes
- Overlooking self-referencing in protection area setup
- Misinterpreting the block number in multi-channel programs
Seeing Multiple Alarms?
Seeing another alarm with this one? Enter the code.
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