I am trying to achieve something similar. I have 11 S7-1200 PLC'S 1215 linked in daisy chain. 

I created a modbus tcp server on first plc and tried to access the tags in db through others however i cant get to see the data in server. 

Will the data server db hold be able to entertain read write requests from all plc at one time if server access is open?

Or do i need to create 10 different servers modbus tcp and then access through individual clients for each db? 

Duris_I

Hello,

good sugestions from Einstein you already have but I try also give infos as you want. I see maybe no problem to try set S7-1500 as Modbus TCP Server and each of S7-1200 as Clients. Your Server need have prepared unique connection with each Client independently, I expect 15 Server blocks with own data storage (Holding register for data from Clients). On each Client of course you need Client block with IP of Server and different Port value to differ each Client. Then each Client will have unique MB connection to Server and storage for its data on Server. You can then manage data next as you want (WinCC,...). I see this procedure little bit hard with preparation but it can work in my opinion, S7-1500 will not have probably problem handle 15 independed TCP connections with S7-1200 Clients and also with WinCC channels. Same similar solution can be OUC but is up to you what solution you select.

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Split from Best way to communicate and program one S71500 PLC and multiple S71200 PLC.