What causes Siemens SINUMERIK alarm 100123?

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 100123?

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 100123 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.

axismd.ai

Siemens SINUMERIK Controller

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

Alarm 100123

Siemens 840D 100123 - Invalid character

SIEMENS alarm 100123 'Invalid character %1' occurs when the SINUMERIK control encounters an unrecognized or improperly formatted character in NC program code, parameter settings, or data input. This servo-category alarm typically fires during program execution or parameter modification when character encoding, special symbols, or syntax errors are detected.

Siemens SINUMERIKProgram/G-codeIntermediate30-120 minutes

100123

Siemens 840D 100123 - Invalid character

Invalid character

Root Cause Summary

SIEMENS alarm 100123 'Invalid character %1' occurs when the SINUMERIK control encounters an unrecognized or improperly formatted character in NC program code, parameter settings, or data input. This servo-category alarm typically fires during program execution or parameter modification when character encoding, special symbols, or syntax errors are detected.

Safety

Refer to Siemens documentation
Ensure qualified technician performs repairs

Causes and Fixes

1
Check program editor character set
Access HMI → Program Manager → Settings and verify character encoding is set to ISO 8859-1 or UTF-8. Check MD11210 $MN_CHARSET_MODE setting.
Always use standard ASCII characters (32-126) in NC programs for maximum compatibility
2
Scan program for invalid characters
Open the NC program in Program Editor and search for non-standard characters, especially after copy/paste operations from external sources.
Backup original program before making character corrections
3
Re-save program with correct encoding
Use HMI text editor to re-save the program, ensuring proper character encoding. Check MD11200 $MN_CHAR_SET_DISPLAY for display character set.

DIY Feasiblehigh confidence

Call a technician if:

·Hardware communication failures persist
·Parameter corruption affects multiple systems
·Safety-related servo parameters involved

Prevention

Use only standard ASCII characters in NC programs
Regular backup of machine data and parameters
Avoid copy/paste from external text editors
Implement proper EMI shielding for communication cables

Common Mistakes

Using special characters from word processors
Ignoring character encoding settings
Not backing up parameters before modifications
Assuming all text editors produce compatible character sets

Related Alarms

100124 380001 300500

Seeing Multiple Alarms?

Seeing another alarm with this one? Enter the code.

Get machine-aware diagnosis

AxisMD logs alarms against your actual machines, tracks patterns, and gives AI context your manual doesn't have.

Start free

Was this guide helpful?

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