Hello Krzysztof;

Could you please explain in more detail what you intend to do with your repeater? It is not clear to me based on thhe original description. A schematic would probably help to show what you need.

Here are somegeneral considerations on Profibus networks and repeaters. Basically, aProfibus-DP network is based on RS-485 recommendations,and at a minumum it cannot extend for more than a single segment; a segment is limited to 32 nodes, or to a distance/bus speed calculation. If you want to talk to more than 32 nodes (up to a maximum of 125 nodes on the network) or go further distances (up to 1 km over copper) then you must use a repeater to regenerate and re-transmit the signal..

All nodes and segmentsconnected through a repeater (or more than one) are part of a single network, However, nothing in the RS-485 specifications limits the node definition to a single master and multiple slaves, Many masters can share the bandwith on a Profibus network, through token exchanges which allow only one participant totransmit at a time. Since HMIs and SCADA PCs are masters (class 2) they can also participate in a Profibus network. Also, more than one class 1 master (your PLC, for example) can coexist on the network, but only one class 1 master can own the outputs of a DP-slave.

If these considerationsdo not clarify your issue, please return to the thread with more details.

Hope this helps,

Daniel Chartier

New question published byDrG is split to a separate thread with the subject repeater, we can't connect more then two ET200S.

Best regards
Min_Moderator