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Siemens SINUMERIK Controller
Program/G-code · Intermediate · 30-120 minutes
Siemens 840D 104031 - There is no preselected tool
Alarm 104031 occurs when the CNC program attempts to execute a tool change or tooling operation without a valid tool being preselected. The control system expects a T-word (tool preselection) command to have been executed before the M06 (tool change) or before certain machining operations that require tool data.
104031
Siemens 840D 104031 - There is no preselected tool
There is no preselected tool
Siemens SINUMERIK alarm 104031: There is no preselected tool. This alarm indicates a required configuration element, parameter, or program component is missing or has not been set up.
Root Cause Summary
Alarm 104031 occurs when the CNC program attempts to execute a tool change or tooling operation without a valid tool being preselected. The control system expects a T-word (tool preselection) command to have been executed before the M06 (tool change) or before certain machining operations that require tool data.
Safety
- Refer to Siemens documentation
- Ensure qualified technician performs repairs
Causes and Fixes
- 1
Review the NC program at the point where the alarm occurred and identify the M06 command line number.
- 2
Check if a T-word command (e.g., T1, T5) exists in the program lines immediately before the M06 command.
- 3
If missing, insert the appropriate T-word command on the line before M06 (e.g., N100 T1 followed by N110 M06).
Ensure the tool number specified matches an existing tool in the tool management system.
- 4
Reset the alarm, restart the program from a safe position, and verify the tool change executes correctly.
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