What causes Siemens SINUMERIK alarm 104201?

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 104201?

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 104201 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 104201

Siemens 840D 104201 - Error on setting/resetting semaphores

Alarm 104201 indicates a semaphore handling error in the NC program, typically occurring when synchronized actions or resource locking operations fail. This happens when SET or CLEAR semaphore commands are improperly configured, semaphore resources are exhausted, or conflicting semaphore operations occur between channels or programs.

Siemens SINUMERIKProgram/G-codeIntermediate30-120 minutes

104201

Siemens 840D 104201 - Error on setting/resetting semaphores

Error on setting/resetting semaphores

Root Cause Summary

Alarm 104201 indicates a semaphore handling error in the NC program, typically occurring when synchronized actions or resource locking operations fail. This happens when SET or CLEAR semaphore commands are improperly configured, semaphore resources are exhausted, or conflicting semaphore operations occur between channels or programs.

Safety

Refer to Siemens documentation
Ensure qualified technician performs repairs

Causes and Fixes

1
Review the NC program around the alarm occurrence for SET and CLEAR commands. Verify syntax matches format: SETM(semaphore_number[,channel]) or CLEARM(semaphore_number[,channel]).
2
Check that semaphore numbers used are within valid range (1-16 for most 840D systems, verify in machine data 10722 $MN_SEMAPHORE_MAXCOUNT).
3
Ensure every SETM command has a corresponding CLEARM command and that semaphores are not cleared before being set or cleared multiple times without resetting.
4
Test the corrected program in single block mode to verify proper semaphore sequence execution.
Always backup original NC programs before making modifications.

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