Siemens SINUMERIK codes
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Siemens SINUMERIK Controller

PLC · Intermediate · 30-120 minutes

Alarm 400127

Siemens 840D 400127 - Delete DB 27 in the PLC and restart

This alarm occurs when the size of DB 27 created by the basic program differs from the existing DB in the PLC, typically due to program or configuration mismatches. Fix by deleting DB 27 in the PLC and restarting.

Siemens SINUMERIKPLCIntermediate30-120 minutes

400127

Siemens 840D 400127 - Delete DB 27 in the PLC and restart

Delete DB 27 in the PLC and restart

Siemens SINAMICS drive alarm 400127: Delete DB 27 in the PLC and restart. This alarm indicates a fault condition in the SINAMICS servo drive system. Refer to the Siemens SINAMICS fault list documentation for the complete remedy.

Root Cause Summary

This alarm occurs when the size of DB 27 created by the basic program differs from the existing DB in the PLC, typically due to program or configuration mismatches. Fix by deleting DB 27 in the PLC and restarting.

Safety

  • Refer to Siemens documentation
  • Ensure qualified technician performs repairs

Causes and Fixes

  1. 1

    SAFETY: Stop machine and ensure safe state

    CRITICAL: Stop all machine operations, ensure spindle is stopped, and put machine in safe state before accessing PLC data.

  2. 2

    Backup current configuration

    Create a complete backup of PLC program and data blocks before making any changes.

  3. 3

    Access PLC data with proper authorization

    Navigate to the PLC data blocks in the Siemens control system interface using appropriate access level.

  4. 4

    Delete DB 27

    Locate and delete DB 27 to clear the mismatched data block.

  5. 5

    Controlled system restart

    Restart the CNC system to regenerate DB 27 with the correct size. Verify all safety systems are functional after restart.

Service Recommendedmedium confidence

Call a technician if:

  • ·If not trained in PLC programming and data block management
  • ·If the alarm persists after deleting DB 27 and restarting
  • ·If unable to access or modify PLC data blocks
  • ·If unsure about safety procedures or machine lockout

Prevention

  • Verify program updates before execution
  • Backup PLC data blocks before making changes
  • Ensure proper training before modifying PLC data
  • Follow proper change management procedures

Common Mistakes

  • Not restarting the system after deleting DB 27
  • Overlooking parameter mismatches in the basic program

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