Hi guys,

I am having this pending issue now with the S7-300 plc,
Both Plc's in separate panels are indicating : System fault [SF] with a steady constant red indication while on the other hand the BF still blinks red continuous. Both errors occurs the same time on the CPU of these two PLC.

However, i have checked the profibus dp cables. I really need your ideas.

Thanks.

I had a similar problem with s7-300.It turn out that the PLC input card with sf red light was faulty and had to be replaced.My machine worked fine after that.