: Send a localized target startup command using the Siemens operator panel (BOP/IOP) or via the Siemens SiePortal Software.
To get the most out of your Siemens drive and avoid unnecessary A07991 alarms, follow these expert tips.
: Usually implies a communication bit (Bit 10) from the PLC is at "0" level, preventing the drive from responding.
One of the "best" advanced uses of this feature is as a diagnostic tool for existing equipment. Experienced engineers set to activate the "static measurement". When started, this routine not only measures parameters but also checks for critical faults:
The fault code "0A7991" seems to be specific and might relate to one of Siemens' product lines. Here are some general steps you might consider to find the information you're looking for: siemens fault 0a7991 best
The next time you see , you can now take a deep breath. It's not a cry for help from your drive, but an announcement that it is ready and waiting for its final calibration step. By following the best practices in this article, you can turn a notification into a perfectly tuned motor in just a few minutes.
If you want the best performance, let the drive finish its measurement:
command. The motor may "whistle" or remain still while identifying.
💡 If your PLC cycle time is too high, consider moving non-critical logic to a different cyclic interrupt (OB) to prioritize the motion control communication. When to Contact Siemens Support : Send a localized target startup command using
: The alarm most often appears when you have triggered a motor identification (p1910) but haven't yet started the motor to let the drive measure its characteristics. Incomplete Configuration
I should also search for "Siemens 0A7991 best practice" and "Siemens A7991 clear". have gathered a substantial amount of information. I need to write a comprehensive article that covers: definition and meaning, triggers and causes, Siemens model series, step-by-step solutions, when it's paired with A08526, p1900 and p1910 parameters, best practices, advanced troubleshooting, frequently asked questions, and resource recommendations. I will cite the sources I've found. the world of industrial automation, encountering an alarm on your Siemens drive can be an instant source of anxiety. You may have seen code A07991 (often displayed as A7991 on the operator panel) flash across your screen. The good news is that this isn't necessarily a "fault" as you might think. In fact, the keyword for this scenario is likely the best one you could hope for: . This article will serve as your definitive guide to understanding this message and finding the best, most efficient way to resolve it.
A maintenance tech named Alex saw alarm 0A7991 appear on a Siemens 840D sl after a power outage. The machine wouldn’t reference an axis. Instead of panicking, Alex checked the drive status via the HMI: the drive was reporting "ready" but the NCK showed the axis as parked. The best fix? Alex went into the startup menu → axis replacement → reparked the axis, then reinitialized the drive parameters from a backup. After a warm reboot, the fault cleared. Lesson learned: 0A7991 often means the NC and drive disagree on axis presence — reparking or re‑acknowledging the drive solves it best.
Complete Engineering Guide to Troubleshooting Siemens Alarm A07991 One of the "best" advanced uses of this
: After the alarm disappears, ensure you perform a Copy RAM to ROM (e.g., set p0971 = 1 ) to permanently save the new motor data, otherwise, the alarm may return after a power cycle. Common Troubleshooting Steps
Choose (if the load cannot spin) or Rotating (for better accuracy).
Master Guide: Troubleshooting Siemens Alarm A07991 Best Practices The Siemens Sinamics drive alarm A07991 Go to product viewer dialog for this item.
