Index Modification Writes to System Device
Mitsubishi Electric · MELSEC-Q/L Common Instruction
¿Qué significa 1103 ?
This error occurs in Basic model QCPU, High Performance model QCPU, Process CPU, and Redundant CPU when data, after being modified by an index register, attempts to write to a device reserved for system use. While device range checks aren't always conducted, writing to a system device specifically triggers this error, indicating a critical memory access violation and potential system instability.
Causas comunes
- Program logic using indexing (e.g., X10Z0) results in an address pointing to a system-reserved device range.
- An indexed write operation bypasses standard device range checks and targets a protected system memory area.
- Improper calculation of indexed addresses leads to an unintended memory overwrite.
Pasos de reparación & Lista de verificación
Haga clic en los pasos para seguir su progreso.
- 1
Review the program logic where index registers (e.g., Z0) are used in conjunction with write instructions.
- 2
Carefully calculate the maximum possible address that an indexed instruction can access in a given program segment.
- 3
Adjust device assignments or limit the range of index registers to prevent access to system-reserved device ranges.
- 4
Verify the CPU type and its specific handling of device range checks during indexed operations.