Communcation between 2 s7-300 systems

Hi everyone,
At a plant I work at, they have 2 S7-300 systems already running, one is the CPu315-2dp with a mp277 and 2 eurotherm controllers all talking on Profibus.

The other is a CPU315f-2 PN/DP with 15 or so Danfoss FCD300's and a couple of ET200M's and a mp277 running on it.

They have asked me to connect the 2 together so that from one HMI screen they can look at data on the plc it is not on the current network with.

Do I need to purchase a DP coupler? or can I rearrange node addresses and make it all one network having both CPU's do run as they did and just a couple of SFC/FC to send data between them?

If one of the PLCs has the XPUT and XGET built-in SFCs, you can communicate over the MPI bus. That way all you need is to change the MPI address of one of the PLCs, some Profibus cable and a couple of connectors. And of course you'll need to make some changes to the program.

Kind regards,

Boxy doesnt say how the ET200M's and the MP277 are connected to the 315F-2PN/DP. But if the MPI/DP port is used with the DP slaves, then the MPI option is not possible.
I would not try to connect everything with the same DP network. The entire DP network will be handicapped performancewise, and inflexible for maintenance.

Also, I would not use one of the PLCs as a mailbox for the other PLC. That would make the other PLC dependant on the first PLC, and it is very inflexible with regards to making the HMI program as you cannot freely access the tags in the PLC.

I would add ethernet to the 315-2DP. Either add a CP343-1 LEAN, or exchange it for a 315-2PN/DP.
Then you can freely access the programs of both PLCs from the new HMI.

If adding the CP343-1 LEAN is out of the question, then consider to use a panel that has both MPI and Ethernet onboard. Then connect to one PLC via MPI, and to the other via Ethernet.

A final option is, if both PLCs have their own HMI panel attached, and these panels have ethernet onboard, then you can access these panels remotely via Smartaccess. Either one panel takes over the other, or a 3rd panel uses the two panels as the sources for its own tags.

So is it possible to have 2 completely separate profibus networks run on the same cable and not interfere with one another?
Thus if i connect it all up it both networks will continue to run as if i had never done anything?

So is it possible to have 2 completely separate profibus networks run on the same cable and not interfere with one another?
Thus if i connect it all up it both networks will continue to run as if i had never done anything?

Click to expand...

No, they can coexist, but will interfere with each other. The performance will drop markedly. And with an F CPU, I suggest that you dont touch the DP network on this CPU at all. And there are other diasadvantages.
With the emergence of affordable ethernet options, it is much smarter to go in this direction.

Thanks Jesper,

We've decided to go with replacing the 315-2dp with the dp/pn option since that plc is already running a full rack without going to a second. Thankyou for all your advice. Really appreciated