X-change signals between two Simatic S7-400

I am trying to x-change a few signals between two Simatic CPU:s (414-2DP) via profibus dp.

Can anyone tell me how? I know that one of them must be a master and the other on must be a slave. I must have them in separate projects in Step7 (simplifying the changes in the future)

I wont to have one "Transmitt DB" sent to the receiver PLC and stored in a "Receive DB" in both directions.

What is the simplest way to do this? I have worked a lot with programming but not much with profibus communications.

//Björn

Hi bjojo.

No, the two PLCs dont necessarily have to be master+slave.
You could use master+master.
Create a STEP7 project with both S7-400 PLCs.
In NetPro, create a connection between the CPU's.
You can then program PUT and GET instructions in either PLC with the connection ID.
There are other possible solutions, but the one I mention above is the most "normal" I would say.

Note: In case others are reading this and they consider to do the same with the integrated DP ports in S7-300, then be warned that you cannot do the same because the integrated DP ports in S7-300 cannot initiate a connection (can be server, but not client according to specs). If you try to create a connection via the integrated DP ports in two S7-300 you will find that it is not possible.

Hi again.

I see now that you want to have separate projects.
I think that it is not a good idea, even if you think it will simplify things. My experience is that the integration is a good way to keep everything in sync.

If you insist to have separate projects, then it is still possible.
You have to create "dummy" CPUs in each of the two separate projects. The "dummy" being the other CPU that the CPU in each project has to exchange data with.
Carefully replicate the connection setup in Netpro for each project, and it should still work.

bjojo said:

I am trying to x-change a few signals between two Simatic CPU:s (414-2DP) via profibus dp.

Click to expand...

Hi Björn

If Your signals are from binary interlocks to "few"-words both directions. Then the DP/DP coupler is good equipment for this purpose. Then the both Profibus-networks are intependent from each others and the both CPU's can be a bus master.

-Pete-

[FIN]Pete.

I just want to comment that there are nothing wrong with having several masters in the same Profibus network.
"multi-master" is a feature of Profibus.
There could be reasons to put in a DP/DP coupler, but if bjojo just have the two S7-400 CPUs in the entire system, then I cant see that a DP coupler is justified.

JesperMP said:

I just want to comment that there are nothing wrong with having several masters in the same Profibus network.
"multi-master" is a feature of Profibus.

Click to expand...

Hi JesperMP

Yes, You are right, there is nothing wrong to use several masters in the same Profibus network.
In this case, Björn wanted some advices how he can communicate between the two PLC which are in separated projects. DP/DP-coupler is only one way to do it.
I justify my choose: 1) PLCs are in separate projects 2)There is a calvanic isolation between the PLCs 3)The both Masters can have different baud rate settings 4) I have some other argumets too, but I finish the list here.

All good for You :nodi:
- Pete -