417-5ＨCPU，PLC停止运行，报警代码如下：

Event 1972 of 2085:  Event ID 16# 4535

DEFECTIVE: canceled by watchdog/processor exceptions

No relevance for user: 0545 041f 0000

Previous operating mode: RUN

Requested operating mode: DEFECTIVE

Internal error, Incoming event

09:07:53.147 PM  09/18/2022

(Coding: 16# 4535  FF8D  0001  0545  041F  0000)

故障时ｓｔｅｐ７软件不能链接PLC，CPU开关不能重启，电源断电还是不能重启，最终ＭＥＲＳ后，重新转载程序后，启动运行程序，各位大佬这个故障到底是什么原因引起的啊。