故障描述：CP443-5下挂两个RS485中继器跟9个从站（4个I/O从站，5个绝对值编码器）。设备正常生产过程中这条网络无规律的出现闪断，有的时候一两个从站掉线，有的时候9个站几乎同时掉线，片刻后自动又恢复正常，有时候一两天来一次，有时候一天七八次。系统里一共3条DP网，另外两条网络DP/MPI跟DP都没异常现象。现在中继器接线，DP头，终端开关，DP电缆屏蔽都检查过了，CP卡硬件版本7.1，组态7.0也没问题，至于噪声这一块机组调试期间几个月的空载有载运行期间从未出现过类似问题，是最近才新出的故障，感觉应该不是电缆走线的问题。程序用OB86监视故障发现其中有几次故障发生时DP Master主站故障先来了，然后才是从站挨个掉线。所以现在怀疑会不会是CP443-5的问题？希望各位有过类似经历的同仁给点建议，如何确认是不是DP主站也就是CP卡的问题，或者有没有什么好的解决方案，以下是在最新的诊断日志：

Event 1 of 204: Event ID 16# F9C1:2317
DP master information:
Currently configured number of slaves: 9
Currently polled number of slaves: 9
Currently configured number of slaves to poll: 9
Currently configured number of slaves not to be polled: 0
External error, Incoming event
11:39:56.144 AM 01/09/1994
(Coding: 16# F9C1 2317 0200 0000 0909 0900)


Event 2 of 204: Event ID 16# F9C1:200B
Module entering the logical token ring in the STEP E mode.
Normal data exchange can be resumed
External error, Incoming event
11:39:56.093 AM 01/09/1994
(Coding: 16# F9C1 200B 0200 0000 0000 0000)


Event 3 of 204: Event ID 16# F9C1:2000
The module has dropped out of the logical token ring.
Due to a problem on the bus or due to an incorrect or missing configuration, no data transfer is possible. Other possible cause: Reconfiguration changed the module to a passive bus node.
External error, Incoming event
11:39:51.103 AM 01/09/1994
(Coding: 16# F9C1 2000 0200 0000 0600 0000)