Modbus Communication issues

[EngYoug006]

Hi everyone,

We are constantly facing communication loss between Modbus Devices (TeSys, ATS48, PM8000, SEPAM...) and PLC (M580 Hotstanby) in our Ecostruxure Hybrid DCS system ,  with recurrent following alarms for instance; Device warning, Device Failure, Comm Error, ... (refer to Alaram File.pdf). Note that this issue occurs on different zones, devices stop randomly which increases plant downtime. 

We explored and checked many possibilities  (Earthing, harmonics, made some software changes on both filed and PLC side: Hybrid DCS template and DFBs;  Egx Gateways settings or eNOC port settings; hardware issues such as cables, gateways or switches... see COM Diagnostics.pdf )but still couldn't solve the problem.

Thank you