Mitsubishi PLC system,

Mitsubishi PLC system, have intermittent communication lost, between 5 PLC CPU.
L. Err red LED flashing on the communication module QJ71BR11. checked cable, clean connector. Pin,
still happen occasionally , any one can help?

I would verify the settings on the master to ensure that there are 4 stations set on the network and the shared address parameters are all configured. Also make sure they are all set properly on the station numbers and the network number in the network parameters matches on all units. Also check the mode switch on all units.

https://www.google.ca/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwjklZrl9pDLAhUog4MKHXlnAlgQFggbMAA&url=http%3A%2F%2Fwww.omniray.ch%2Fmodulare-sps-system-q.html%3Ffile%3Dtl_files%2FKatalog%2FHandbuecher%2FSteuerungs-UndRegeltechnik%2FSPS-Systeme%2FModulareSteuerungen%2FSystem-Q%2FKommunikation%2FQJ71-LP21-25-G-BR11-MelsecNetHNetworkModule_UserManual-Installation_IB-080049-M.pdf&usg=AFQjCNFZlBN4ba77kAY8g-6ktMYMESeLvw&bvm=bv.115277099,d.amc

Hope this helps,