Profibus data exchange betven 6 masters and slave

Hi Mike,

I have made a small S7-project with the MPI communication (max. 84 byte / CPU) like calmdown have suggested. When you choose "Define Global Data" on the MPI-Bus with the right mousekey, then you can see the data transfer for MPI.

Another is thecommunication with the DP/DP-couplers, there you may use 240 byte input and 240 byte outputfor each CPU 314. This is also in the project.

Another possibility is using the CP 342-5, then you can also use 240 byte for the communication when you use Profibus FDL. The same CP is to use as a slave on Profibus DP.

Another possibility is using 6 * CP 343-1CX10 Lean and a PN CPU or a CP 343-1EX21 as controller for Profinet, the Lean CPs can be then the devices for Profinet.

The two last solutions are not in the project, but you have first to decide what you want.

When the price is the isue then is the MPI solution the best, have you thought about one PLC with the 6 drives under it? When the DP/DP-couplers are cheaper then the CP 342-5 then is that the next solution, when you didn't have enough with 84 byte (input + output together)to communicate between the 7 CPUs, you have then the possibility to use 240 bytes in- and output. With the CP 342-5 you have two possibilitys Profibus FDL or Profibus DP with also 240 byte in- and output. When that is also not enough then you may use Ethernet or Ethernet with the protocol Profinet where you can use even more bytes.

[quote user="Miki Rapaic"]

1. At first I want to use MPI-s for HMI panels (every of 6 PLCs has its own panel)...

2. But let's say i use MPI connection for data exchange like I described before, and I use profibus connection for PANELs, will the HMI panel work right because the PLC is MASTER (profibus) ...and PANEL will be added to it ......

3. Will I be able to control PLC from HMI panel on this way?

4. How fast is MPI connection.And will I be able to communicate with all 6 or 7 PLCs?

Hi Miki,

Thanks for the thanks....

The answers:

1. no problem;

2. Both, the CPU and the Panel are master on the bus (if you use a Siemens Panel), thats no problem because Profibus can have multiple masters, like the project that I have made for you where 6 masters are on the Profibus with 6 drives and also 6 DP/DP-couplers;

3. That will work for sure, thats where Profibus is for! You even can take one bigger panel for all the PLCs, when you use then also Report System Error then you have also all errors from the system when there is something wrong (look to the parameters of the several panels how many CPUs can be communicate);

4. MPI is for this PLCs 187,5 kBit/s and you can communicate 84 Byte as maximum for each CPU, so PLC1 can communicate 84 byte with all the other, PLC2 can communicate 84 byte with all other and so on {It is not much but when it is enough then is it the cheapest way.