Use 2 onboard PN connectors for the PNIO ring, and the remaining 2 PN connectors for the DCS modbus communication

I have the same task, but something extra:I also have PN IO system.

My idea was to use 2 onboard PN connectors for the PNIO ring, and the remaining 2 PN connectors for the DCS modbus communication.

But I got a request to poll 5 slaves.

With DCS+PN IO system all my PN connectors are used up already, do I need CP 443-1 for polling the slaves or can it be done with a switch? Sample connection scheme would be very appreciated...

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Edit

Or, something to convert Modbus <-> Profibus?

And I can use the intergrated Profibus connectors?

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I was thinking this hardware config

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Split from S7-416H onboard PN support both Master and Slave at the same time?.

In the DCS-PLC connection, the S7-400 will be the server.

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The original idea was this:

PNIO ring with 4x ET200M HF.

Remaining onboard PN connectors to Modbus master (client).

For this, the hardware is already bought and this is no new thing.

The plus is that now I have to insert 5 slaves. Can I connect a DP-Modbus converter to a redundant system with a Y-link?

Hi,

The 5 additional devices which came into consideration in a late point of time, are on modbus tcp protocol.

Sorry if I wasn't clear, I was never good at explaining so bear with me. 

Redundancy is only needed in the controller and its connection to the DCS.

All the io system has to be connected to the H-system but not be redundant in itself. The 5 servers would connect to the red. Profibus network via a Y-link and a PB<->Modbus gateway.