Siemens Fault 0a7991 'link' -

in Siemens drive systems (such as SINAMICS G120, G130, or S120) is an (not a fatal fault) indicating that Motor Data Identification is active

1. Manually rotate motor shaft (power off & locked out). If it doesn’t turn freely → mechanical jam.
2. Check motor brake – Listen for release click; measure brake voltage.
3. Verify torque limits – Compare with required starting torque.
4. Review encoder wiring – Especially for new installations or after maintenance.

: Simply wait for the measurement to complete and the alarm will disappear automatically once the drive is switched to "Ready." F07900 (Drive: Motor locked/speed controller at its limit) siemens fault 0a7991

Conclusion: Master Your Siemens Drive’s Language

Before diving into the causes, it is important to recognize how this fault manifests in a live production environment: in Siemens drive systems (such as SINAMICS G120,

Based on Siemens documentation and technical support resources, the following are possible causes of fault code 0A7991: Manually rotate motor shaft (power off & locked out)

Troubleshooting Steps

Ensure the motor is at a standstill and the configuration is complete.

• Replace the suspect module with a known-good spare (same order number and firmware version).
• If the fault clears, the original module is defective.
• If the fault remains, the issue lies elsewhere (cabling, configuration, or backplane).