OPC communication or MODBUS
We are using serial communication with modbus RTU protocol and RS485 for communication of data between DCS ABB80XA and ESD Hima plc. However, speed of transmission data is very slow (takes about 4 second to get data form ESD or vice versa). Someone has advised us to use OPC server to send and recieve data between this two. I wonder if we need to do this? I mean what are pros and cons of OPC server. If we use OPC server we actually adding a server to our system and this affects maintennace of it and problems that might happen later that is even worse than speed for example troubleshooting in case of OPC server has issue. Anyway my question is that OPC communication is safe or not? second question is that if slow speed of communication with modbus is something that can be tackled and fixed and no need to use another protocol. appreciate any helpful replies.
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Check the cycle time of the Modbus read requests in the AC800M program. If the cycle time is 4 seconds, then thats your problem - request data faster.
If the AC800M is waiting for several seconds to get the data from the Hima PLC then check the ESD. You should expect the ESD to respond almost immediately to the request.
When polling time is reduced master will start sending more requests per sec.