What causes Siemens SINUMERIK alarm 401502?

Invalid axis number passed to FC15 in the PLC program. FC15 called with a parameter that exceeds the valid range for this SINUMERIK configuration. PLC program version mismatch — FC15 call parameters not updated after a machine configuration change. Number of configured axes in SINUMERIK does not match the FC15 parameter. PLC program downloaded with incorrect machine data for this specific machine tool.

How do I fix Siemens SINUMERIK alarm 401502?

1. Check the SINUMERIK PLC alarm details for the specific parameter value that caused the error. 2. Review the PLC program — find the call to FC15 and verify the parameter values are within valid range. 3. Compare the FC15 parameter against the actual number of configured axes in the SINUMERIK machine data. 4. If the PLC program was recently modified or the machine configuration changed, verify FC15 calls were updated accordingly. 5. Contact the machine tool builder if the PLC program source is not available for review.

Siemens SINUMERIK codes

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Siemens SINUMERIK Controller

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

Alarm 401502

Siemens 840D 401502 - Impermissible axis no. parameter in FC 15

This alarm occurs when an axis number parameterized in FC 15 does not exist on the machine. Correct the program by specifying a valid axis number.

Siemens SINUMERIKProgram/G-codeIntermediate30-120 minutes

401502

Siemens 840D 401502 - Impermissible axis no. parameter in FC 15

Impermissible axis no. parameter in FC 15

Siemens SINUMERIK alarm 401502: Impermissible axis no. parameter in FC 15. An impermissible or invalid parameter was passed to PLC function block FC15. This indicates a PLC programming error or configuration mismatch in the machine tool builder ladder program.

Root Cause Summary

This alarm occurs when an axis number parameterized in FC 15 does not exist on the machine. Correct the program by specifying a valid axis number.

Safety

Refer to Siemens documentation
Ensure qualified technician performs repairs

Causes and Fixes

1
SAFETY FIRST - Stop all operations
Ensure machine is in STOP mode and all axes are stationary before making any program changes.
2
Locate the error
Check the alarm message for the specific block or line number causing the issue.
3
Verify axis number
Ensure the axis number in FC 15 matches a configured axis in the machine data (MD30100-30107).
4
Test the fix safely
Clear the alarm, perform a dry run or simulation first, then test at reduced feedrate with operator present.

DIY Feasiblemedium confidence

Call a technician if:

·If the alarm persists after verifying axis numbers
·If machine data appears incorrect or inaccessible
·If you are not authorized to modify machine parameters
·If unsure about machine configuration

Prevention

Always validate axis numbers against machine configuration before running programs
Use simulation mode to catch syntax errors early
Maintain documentation of valid axis assignments for each machine
Implement program verification procedures before production runs

Common Mistakes

Using axis numbers from a different machine
Overlooking subprogram references to invalid axes

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