What causes Siemens SINUMERIK alarm 104102?

Part program contains an illegal or unsupported command for the current machine configuration. Parameter or machine data setting incompatible with the commanded operation. Required option or function not enabled on this SINUMERIK control. Incorrect axis assignment or configuration for the commanded function. Software version or compile cycle version mismatch.

How do I fix Siemens SINUMERIK alarm 104102?

1. Note the full alarm message including any parameter values shown (e.g., axis number, block number, channel). 2. Identify the program block or operation that triggered the alarm. 3. Review the SINUMERIK alarm manual for alarm 104102 to identify the specific cause and remedy. 4. Check the relevant machine data parameters referenced in the alarm. 5. If the alarm persists after correcting the program, contact Siemens technical support with the full alarm text and machine data backup.

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Siemens SINUMERIK Controller

Program/G-code · Intermediate · 30-120 minutes

Alarm 104102

Siemens 840D 104102 - PA: Error on reading number of T nos.

This alarm occurs due to an error in reading the number of tool numbers (T nos.) in the program, often caused by incorrect syntax or unsupported functions. Correct the program or verify control options to resolve.

Siemens SINUMERIKProgram/G-codeIntermediate30-120 minutes

104102

Siemens 840D 104102 - PA: Error on reading number of T nos.

PA: Error on reading number of T nos.

Root Cause Summary

This alarm occurs due to an error in reading the number of tool numbers (T nos.) in the program, often caused by incorrect syntax or unsupported functions. Correct the program or verify control options to resolve.

Safety

Refer to Siemens documentation
Ensure qualified technician performs repairs

Causes and Fixes

1
Safety first - Stop machine operation
Ensure machine is in a safe state, spindle stopped, and program execution halted before making any changes.
2
Locate error block
Check the line number in the alarm message and open the program to find the specific block.
3
Fix tool number syntax
Ensure the T number is correctly defined and within valid range for the control (typically T1-T999 depending on system).
4
Test program in simulation mode
Use dry run or simulation mode first to verify the fix before actual machining operations.

DIY Feasiblemedium confidence

Call a technician if:

·If the alarm persists after syntax correction
·If the required control option cannot be enabled without assistance
·If you are not familiar with CNC programming or safety procedures
·If machine behavior becomes unpredictable

Prevention

Always validate tool numbers before running the program
Use simulation mode to catch syntax errors early
Maintain a log of valid tool numbers for your specific machine
Regularly backup working programs before modifications

Common Mistakes

Overlooking the specific line number in the alarm
Using tool numbers outside the control’s defined range

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Always verify with your machine manual or a certified technician before performing service procedures.