Siemens G120 F01105 — What It Means
F01105 on a Siemens SINAMICS G120 indicates that the Control Unit (CU) does not have enough available memory to complete a task. This can happen during parameter handling, project loading, firmware downloads, or internal processing operations. The fault is logged as ‘CU: Insufficient memory’ in the drive’s fault buffer. Unlike motor or power-stage faults, this code points directly to a problem with the Control Unit’s ability to manage data, either because the parameter set is too complex, the project file is corrupted, or the CU hardware itself has failed.
Common Causes
- Oversized or complex parameter set A project with too many parameters or advanced features can exceed the CU’s memory capacity during loading or runtime.
- Corrupted parameter data Incomplete or inconsistent parameter uploads, downloads, or copies can create memory allocation problems inside the Control Unit.
- Failed firmware or project download An interrupted or mismatched firmware update or Startdrive/TIA project transfer can leave the CU in a state where memory is not properly managed.
- Firmware and hardware mismatch Installing a project configured for a different CU model or firmware version can cause memory handling errors during commissioning.
- Control Unit hardware failure If the fault returns immediately after a clean parameter reset and power cycle, the CU’s internal memory or electronics may be damaged.
Step-by-Step Fix
- Read the fault buffer using the drive’s diagnostic parameters or HMI to confirm the exact fault code, time stamp, and any additional context stored in the CU’s fault memory.
- Identify recent changes by reviewing what was done before the fault appeared, including parameter uploads, project downloads, firmware updates, or Control Unit or Power Module replacements.
- Back up the current parameter set if possible, then perform a controlled parameter reset or reload a known-good commissioning project to rule out corrupted data as the cause.
- Power-cycle the drive completely by disconnecting control and line power for at least 30 seconds, then re-energize and check if the fault clears with a minimal or default configuration.
- Verify hardware and firmware compatibility by comparing the installed Control Unit model and firmware version against the configured project and Siemens support package to make sure no mismatch exists.
- Test with a simplified project by loading only the essential parameters needed for basic motor control, avoiding advanced functions or custom macros that may strain memory.
- Replace the Control Unit if the fault persists after a clean reload and verified configuration, as a recurring F01105 indicates memory corruption or CU electronics failure that cannot be repaired in the field.
Parts Often Needed
| Part | Notes |
|---|---|
| Siemens SINAMICS G120 Control Unit (CU240E-2, CU250S-2, or matching variant) | Amazon | Required if memory fault persists after parameter reload and power cycle, verify exact CU model for your frame size. |
| Parameter backup file or clean commissioning project | Amazon | A verified project reload can resolve data-corruption faults without hardware replacement. |
When to Call a Pro
Call a qualified drive technician or Siemens-certified service provider if the fault returns after you have reloaded a clean parameter set and power-cycled the drive, or if you are not familiar with Startdrive, TIA Portal, or G120 commissioning procedures. Replacing a Control Unit requires proper configuration transfer, firmware matching, and sometimes module coding or slot assignment depending on your system. A technician will also verify that the fault is not related to a larger system integration issue, network overload, or power-supply problem affecting the CU.