楼主：真如1楼说的那样，就在OB86里面些点代码判断一下吧。工作原理：当DP从站故障时，操作系统触发执行一次OB86；当DP从站故障消失时，操作系统再次触发执行一次OB86。利用这个特点写点代码，我将OB86的声明表里面与操作系统接口主要参数说明一下，并举一个参考例子：

L #OB86_EV_CLASS //Event class and identifiers:B#16#38=outgoing event;B#16#39=incoming event

L #OB86_FLT_ID //Error code:(possible values B#16#C1, B#16#C2, B#16#C3, B#16#C4, B#16#C5, B#16#C6, B#16#C7, B#16#C8)

L #OB86_MDL_ADDR //Logical base address of the DP master

L LW 8 //logical base address of an S7 slave or diagnostic address of a standard DP slave

L LB 10 //DP master system ID

L LB 11 //No. of the DP SLAVE ID

L #OB86_EV_CLASS //WHEN THE EVENT OUTGOING ,GOTO M001
L B#16#38
==I
JC M001

L LB 11
L 3
==I
S M 16.3 //SET DP SLAVE3 FAULT MEMORY

L LB 11
L 4
==I
S M 16.4 //SET DP SLAVE4 FAULT MEMORY

L LB 11
L 5
==I
S M 16.5 //SET DP SLAVE5 FAULT MEMORY


BEU

M001: L LB 11
L 3
==I
R M 16.3 //RESET DP SLAVE3 FAULT MEMORY

L LB 11
L 4
==I
R M 16.4 //RESET DP SLAVE4 FAULT MEMORY

L LB 11
L 5
==I
R M 16.5 //RESET DP SLAVE5 FAULT MEMORY

这样上位可以读取这些地址做些故障报警，或者在程序的其它地方再写点报警代码。