Siemens G120 F01001 — What It Means
F01001 on a Siemens SINAMICS G120 signals a FloatingPoint exception. This is an internal software error in the drive’s control unit or application logic, not a motor overload or power-stage fault. The fault occurs when the drive encounters an exception during a floating-point mathematical operation, such as division by zero, overflow, underflow, or an invalid operation. Siemens fault lists map F01001 to this specific condition, and the typical fault reaction is OFF2 (coast stop) with acknowledgment requiring a complete POWER ON cycle.
Because this is a software or data-processing fault, it does not involve the motor windings, DC bus, or external wiring. Instead, the problem lies in the control unit’s firmware, the drive’s parameter configuration, or application blocks like FBLOCKS or DCC charts. If the fault clears after a power cycle, you likely have a transient glitch or configuration issue. If it returns immediately at every startup, the control unit hardware may be defective and require replacement.
Common Causes
- Firmware or software corruption A transient internal processing fault or corrupted firmware in the control unit can trigger invalid floating-point operations.
- Bad application data in FBLOCKS or DCC Inconsistent or erroneous logic in function blocks or DCC charts can feed invalid math operations to the processor.
- Outdated firmware with known bugs Older firmware versions may contain bugs that cause floating-point exceptions, and Siemens may have issued a patch.
- Configuration or parameter errors Recent parameter changes, downloads, or application updates can introduce data that causes division by zero, overflow, or underflow.
- Defective control unit hardware If the fault appears immediately at every power-up and persists after all software checks, the control unit itself may be damaged.
Step-by-Step Fix {#fix}
- Record the fault details from the drive’s diagnostics menu or fault buffer, including the fault code, fault value, and any diagnostic parameters shown on the operator panel or via the commissioning tool.
- Perform a complete POWER ON cycle by removing all power to the drive, waiting for the capacitors to fully discharge (typically 5 minutes), then restoring power and observing whether F01001 clears or returns immediately.
- Check for recent changes to parameters, application downloads, FBLOCKS configuration, or DCC charts, and review the change log to identify any edits made just before the fault appeared.
- Review and update firmware by checking the current firmware version in the drive’s system menu and consulting the Siemens support portal or product manual for the latest approved firmware release for your G120 model.
- Clear the fault and re-test the drive under normal operating conditions after making any firmware or configuration corrections, monitoring the fault buffer to confirm the exception does not recur.
- Isolate application logic by temporarily disabling or bypassing FBLOCKS and DCC charts (if applicable) to determine whether the exception originates in custom application code or in the base drive software.
- Replace the control unit if the fault persists immediately at power-up after all software and configuration checks, or escalate to Siemens technical support for advanced diagnostics and possible hardware replacement.
Parts Often Needed
| Part | Notes |
|---|---|
| Siemens G120 Control Unit (CU240 series or equivalent) | Amazon | Required if fault persists at every startup and firmware/configuration checks have been exhausted. |
| Siemens Starter or SINAMICS commissioning software license | Amazon | Needed to update firmware, review fault buffers, and modify FBLOCKS or DCC configuration. |
When to Call a Pro
Call a certified Siemens technician or contact the Siemens hotline if the fault returns immediately after every power cycle, if you lack access to Starter or SINAMICS commissioning tools, or if you are unfamiliar with firmware updates and application-block configuration. Because F01001 is an internal software exception, successful repair often requires familiarity with Siemens drive programming, fault-buffer interpretation, and control-unit replacement procedures. If your facility does not have the tools or training to update firmware, review FBLOCKS logic, or safely swap the control unit, professional support will save downtime and prevent further configuration errors.