Siemens Fault 0a7991 Best -

Fault code 0A7991 appears in Siemens drive systems, most commonly in the SINAMICS family (such as G120, S120, G130, or G150) or in SIMOTION systems integrated with SINAMICS drives. It is generally categorized as an internal communication or software timing error within the drive's control unit.

The standard plain-text alarm message associated with this fault is: siemens fault 0a7991 best

"CU: Internal communication error"
or
"Timeout for internal data exchange" Fault code 0A7991 appears in Siemens drive systems

This is the #1 cause. For safety, Siemens drives require a pulse enable (ON/OFF1 command via terminal or fieldbus) before they perform motor identification. If the drive is inhibited, fault 0A7991 appears. "CU: Internal communication error" or "Timeout for internal

A hidden gem: 0A7991 frequently appears after a firmware update or when using an older Starter/TIA Portal version.

Date: October 2023
Product Scope: SINAMICS G120, G120C, G120D, S120 (CU2xx-2 series)
Keyword Focus: siemens fault 0a7991 best