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Siemens SINUMERIK Controller
Servo/Axis · Intermediate · 30-120 minutes
Siemens 840D 75015 - Channel block CLC(0) with active TOC
Alarm 75015 fires when CLC(0) command is executed to disable 3D clearance control while tool radius compensation (G41/G42) remains active in the channel. The CLC(0) function flushes the internal block buffer and treats the current clearance control offset as a contour discontinuity, which is incompatible with active TRC and violates NCK interpreter sequencing rules.
75015
Siemens 840D 75015 - Channel block CLC(0) with active TOC
Channel block CLC(0) with active TOC
Siemens SINUMERIK alarm 75015: Channel block CLC(0) with active TOC. This alarm indicates a fault or error condition on the SINUMERIK 840D control. Refer to the Siemens SINUMERIK alarm documentation for the complete description and remedy.
Root Cause Summary
Alarm 75015 fires when CLC(0) command is executed to disable 3D clearance control while tool radius compensation (G41/G42) remains active in the channel. The CLC(0) function flushes the internal block buffer and treats the current clearance control offset as a contour discontinuity, which is incompatible with active TRC and violates NCK interpreter sequencing rules.
Safety
- Refer to Siemens documentation
- Ensure qualified technician performs repairs
Causes and Fixes
- 1
Verify active compensation state in the part program: search for G41/G42 commands preceding CLC(0) in the NC code listing (use Program/Edit menu or Diagnostics > Program Trace).
- 2
Insert G40 (cancel tool radius compensation) before CLC(0) command. Example: G40; CLC(0); This ensures TRC is deactivated prior to clearance control shutdown and buffer flush.
Ensure G40 executes in a separate block before CLC(0) to allow proper state transition in the NCK.
- 3
Verify the corrected sequence in the Diagnostics menu under NCK > Channel > Compensation Active to confirm G40 has cleared the TRC flag before CLC(0) is processed.
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