Siemens Fault 0.a7991 Jun 2026

If the actual telegram from the drive (visible in Start‑Up tool > Drive parameters > r2050, r2060) does not match these MDs, alarm 0.A7991 is triggered.

If you have a mess of telegrams, the DRIVE-CLiQ wiring may be incorrect. Fault 0.A7991 can appear if the NCU enumerates drives in the wrong order due to a ring break or improper cabling.

Ensure all motor parameters (P304–P311) are entered correctly. Run command siemens fault 0.a7991

if the motor data identification was never completed or successfully saved. When parameters are changed that require a new motor calculation. Siemens SiePortal How to Resolve the Alarm

| Attribute | Details | | :--- | :--- | | | 0.A7991 (A07991 / F07991) | | Full Text | Motor blocked / Motor locked | | Drive Series | SINAMICS G120, S120, G120C, G120P, V20 | | Default Reaction | OFF2 (Coast to stop) | | Fault Class | 7 (Mechanical malfunction) | | Severity | High (requires reset) | If the actual telegram from the drive (visible

The drive will not run the motor at the setpoint speed while this alarm is active. Instead, it will perform the measurement routine once the start command is given. How to Resolve A7991

On the HMI (or via Start‑Up Tool), go to Machine Data > NC Machine Data > Axis-Specific . Siemens SiePortal How to Resolve the Alarm |

, G130, or S120) indicating that .

If none of the above solutions work, consider deeper issues: