data link failure between DCS OVATION and SIEMENS PLC

M

Thread Starter

Meshal

We have DCS OVATION which is connected to siemens PLC to monitor fuel treatment plant(Westfalia). Ovation controller communicate to PLC via MODBUS protocol by means of serial link controller RS485, 4 wires. Recently, we have recived DATA LINK FAILURE alarm and all field data lost. The serial link status has APPLICATION TIMED OUT alarm. What could be the reason of this problem ?
 
Please can you give me the wiring diagram for the connection or overview diagram for the system?
Please send it to this email:
aboforat_2005 @ yahoo. com
 
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