Exchange data in "large" Siemens S7 network

Hi there.

I need some advice on the following:

I have 5 S7 projects. (in total including 10 PLC's en 10 MP277 touchscreens or so). Within an S7 project I must be able to program all PLC's (S7 300) and MP277 over 1 connection. (For instance MPI or Profibus). (All PLC's also have a profibus network with ET200S islands)

Futhermore I must be able to create connections between the plc's to exchange simple data. (1 or 2 byte per connection). The catch is I must also communicate between the several projects. (It is not possible to make one large project)

Normally we connect for example 3 plc's and 3 touchscreens via MPI together and use Global data for this simple data exchange. It is my experience that this slows down dramatically when the network increases in size and number of nodes. So in my opinion it is not advisable to connect all plc and touchscreens together in one large MPI network.

How would you guys do this?

The reason I want this:

There are 5 production lines which can operate completely independant. (Thats one of the reasons why we use seperate S7 projects) The communication links are needed for the product packing where there are several routings possible for the products. (So it is possible to pack products from line 1 on the packing machines from line 2 etc)

Thanks you in advance

Is this a future project, or an existing one ?
If you have the possibility, go ethernet.

Something like this just begs for ethernet. Not only does ethernet have much more power, but by using switches the network traffic in one end of the plant doesnt burden the network in the other end of the plant.

In the past I would have suggested that you exchange data via the various PLCs by means of DP couplers. But nowadays I say do it via ethernet. Be careful that the CPUs and eventual CPs support the number of connections you need.

I would suggest using 315-2PN/DPs.
Put the panels on ethernet too.
Let each PLC have its own DP network for i/o. Do not mix DP networks.
You can then exchange data between S7 stations by means of PUT/GET (unspecified connections in separate projects) or T-blocks (does not require preconfigured connections). Each 315-2PN/DP supports 16 connections which is just enough for your application.

For the most this is completly new. 1 Project with 2 plc's is already existing. I was thinking in the direction of ethernet but my lack off knowledge holds me back. (It looks simple enough) I also made an inquiry at my local supplier. Maybe he can get me started with ethernet.

Like always there is a lot off pressure and not enough time. So if I could stick to known systems then I can get started quick. But I think in this case I need to switch to ethernet. (Which I was planning to do for some time...)

I see one issue:

The "old" plc does not have ethernet. I could replace it but there is no budget for that. (...) How to communicate with that one? If I am correct the 315 2PN/DP have ethernet ports and one port wich can be configured as MPI of profibus. I need the profibus for the DP networks so there is no MPI available.

Forget MPI. It is a proprietary standard that is on the verge of becoming obsolete.
OK for small standalone projects with a PLC + one panel. Not for eveything else.

As you describe it, it is not a small project. There ought to be enough money to do the right things. I mean, MP277 panels arent cheap for example.
You could add a CP343-1 to the old 315-2DPs. Problem is that it is quite expensive too. The CP343-1 LEAN only supports 8 connections.

You can also toss the bucket over and rethink the entire strategy.
You could use a separate PLC or PC Station as "data concentrator".
And/or, if the PLC task is not exceptional, you can consider IM151-8 which costs 1/3 of a 315-2PN/DP (has max 8 connections).

If you are not comfortable by doing something radically different, then simply use 315-2PN/DP everywhere incl. the older PLCs.

Thank you JesperMP. My supplier also came up with the ethernet option. So I will start working towards that solution.