可以看看OB86的帮助文档，里面有详细的介绍，很好使的
Rack Failure Organization Block (OB86)

Des cription
The operating system of the CPU calls OB86 whenever the failure of a central expansion rack (not with S7-300), a DP master system, or a station is detected in the distributed I/Os (PROFIBUS DP or PROFINET IO) (both when entering and outgoing event).

If OB86 has not been programmed, the CPU changes to the STOP mode when this type of error is detected.

You can disable or delay and re-enable OB86 using SFCs 39 to 42.