Hi all,

Having issue on all 3 PLC CPU 412-5H . System are all link up and scalance switch are link in a ring loop by fiber optic channel on the scalance switch. I am having issue on all 3 PLC CPU that BUS5F is flashing. How can i check to confirm my profinet IO system have no issue. Please advise.

hi,

a flashing BUS5F means, regarding to the manual:

One or more devices on the PN-IO-interface don´t answer.

manual, chapter 5.3

SIMATIC Fault-tolerant systems S7-400H

have a look in online diagnostic, what the CPU´s are complaining about

hope this helps,

regards,