上位机装CP5611运行WINCC，同315-2DP的DP口用DP方式通讯，同时300的DP口连接两个从站（s7-200+EM277），有时300突然停机，查看诊断信息有以下两条：
尤其第十条不只什么意思？（还有一个现象，刚运行WINCC时通讯时好时坏，切换几次几次画面一般就能正常）
Event 9 of 10: Event ID 16# 4300
Power on backed up
Previous operating mode: No voltage
Requested operating mode: STOP (own initialization)
Incoming event
01:58:11.447 PM 12/05/2007


Event 10 of 10: Event ID 16# 4550
DEFECTIVE: internal system error
No relevance for user (Z1): 72c1
Previous operating mode: RUN
Requested operating mode: DEFECTIVE
Internal error, Incoming event
01:56:32.032 PM 12/05/2007