What causes Siemens SINUMERIK alarm 12620?

Attempting single character access on system variables or predefined variables instead of user-defined variables. Incorrect syntax when trying to access string variable characters in part program. Confusing variable scope - accessing LUD/GUD variables with improper character indexing. Using single character notation on non-string or incompatible variable types.

How do I fix Siemens SINUMERIK alarm 12620?

1. Verify in the part program that single character access (using bracket notation like VAR[n]) is only applied to user-defined variables (LUD or GUD), not system variables 2. Check variable declarations to confirm the target variable is properly defined as a user-defined variable with string data type 3. Review the syntax at the specified block and channel - ensure character indexing uses correct LUD/GUD variable naming convention 4. Consult the variable list in the CNC's variable management to distinguish between system variables and user-defined variables 5. Remove or correct single character access attempts on non-user-defined variables, or convert logic to use proper variable types

Siemens SINUMERIK codes

axismd.ai

Siemens SINUMERIK Controller

Servo/Axis · Intermediate · 20-40 minutes

Alarm 12620

Siemens 840D 12620 - Channel block accessing this variable as single character not

The variable is not a user-defined variable. The single character access is only allowed for userdefined variables (LUD/GUD).

Siemens SINUMERIKServo/AxisIntermediate20-40 minutes

12620

Siemens 840D 12620 - Channel block accessing this variable as single character not

Channel block accessing this variable as single character not

The variable is not a user-defined variable. The single character access is only allowed for userdefined variables (LUD/GUD).

Safety

Refer to Siemens documentation
Ensure qualified technician performs repairs

Common Causes

Attempting single character access on system variables or predefined variables instead of user-defined variables
Incorrect syntax when trying to access string variable characters in part program
Confusing variable scope - accessing LUD/GUD variables with improper character indexing
Using single character notation on non-string or incompatible variable types

Troubleshooting Steps

1Verify in the part program that single character access (using bracket notation like VAR[n]) is only applied to user-defined variables (LUD or GUD), not system variables
2Check variable declarations to confirm the target variable is properly defined as a user-defined variable with string data type
3Review the syntax at the specified block and channel - ensure character indexing uses correct LUD/GUD variable naming convention
4Consult the variable list in the CNC's variable management to distinguish between system variables and user-defined variables
5Remove or correct single character access attempts on non-user-defined variables, or convert logic to use proper variable types

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.