hello experts

let's start a good course for communicating siemens products and another manufacturers in a bus.

i searched a lot in forum and i found that many questions are the same.

i want you to discuss about a system such as i attached it.
let's survey the possible ways for a system such as that.
i have some question about this system

i start.
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3) how can i read and write to other manufacturers modbus supported i/os in a configured network with s7-300 master and et200s slaves?
are there any specific function blocks?

i hope i say my questions clearly.
please help me my friends.

thanks

Splitted from when we use profibus-dp network,what protocol is used?.