Either the network connection (profibus/profinet?) between the PLC controlling the drive is powered off, network connection lost ( Siemens SiePortal How can resolve the alarm Code A7991 - SiePortal - Siemens
The Siemens fault code (often searched as 0a7991 ) specifically indicates that Motor Data Identification is activated . This is not a critical equipment failure but rather a status alarm triggered during the commissioning or configuration phase of Siemens SINAMICS drives , such as the G120, G120C, and G150 series. Understanding Alarm A07991
When this code appears, the drive is notifying you that a motor identification routine has been scheduled or is currently running. This routine is essential for the inverter to learn the electrical characteristics of the connected motor (such as resistance and inductance) to ensure precise control. siemens fault 0a7991
If the alarm does not disappear or prevents the drive from running, use the following methods to resolve it: 1. Complete the Identification Routine
Ensure the motor is safe to move if a "Rotating Measurement" was selected. Once finished, the alarm will clear itself. 2. Manually Disable the Routine Either the network connection (profibus/profinet
If you are performing a without the final motor, attaching a smaller spare motor can sometimes bypass identification faults by providing enough feedback for the drive to initialize. Alarms A 7991 and A8526 - SiePortal - Siemens
Saves parameters from RAM to ROM (perform after clearing alarm). Set to 0 This routine is essential for the inverter to
: Ensure the Profinet/Profibus cable is securely plugged in and the PLC is powered on.
: While this alarm is active—especially if a rotating measurement is selected—you may be unable to save parameter assignments to the ROM until the process finishes. Common Troubleshooting Steps