MPI Communication protocol

[tulip]

I designed 6 pieces S7-300 Plcs and MP277 HMIs.They are contolling different process and they are communicated by mpi.All of hmi have got the other hmis windows.That is operator can control system from any on hmi.(this is supplied from connections on hmi )I used SFC67 and SFC68 system blocks for data transferring between plcs.I communicated two plcs via SFC blocks but I want to communicate the other plc on the net ,no success.These blocks are called in OB35.Must it be adjusted specific parameters (master/slave),is there any parameters I forgot,I dont know,,,

 

[tulip]

I could not take any answer this message.How can I mpi communications between cpu315-2 dp 's?All of plc's are connected via mpi.I used Get Fc block , block is giving error=1 and status=1 .

 

[ivo.maenen]

The MPI-network is for low cost communication between S7-cpu's and HMI only. It uses the same hardware as Profibus (purple cable and connectors).

So are you sure you mean MPI-communication and not Profibus-communication because you have 2-DP cpu's? MPI uses the programmationport.


MPI makes use of global datacommunication (GD). For this you need to

1) give an MPI-adres to every cpu. You can do this in the HW-configuration.

2) configure the GD-table: Simatic Manager select the icon 'MPI' and choose from the menu 'options > define global data'.

 

[tulip]

Excuse me.I was in holiday therefore I could return now.I understand that this mpi communication can be successed with use of global datacommunication.One question.Let say I prepared a GD in Netpro.This GD transferring is enough for one plc or it should transferred to all of plc ?Thanks in advance..

 

[ivo.maenen]

The GD-communication works with broadcast-communication. But each cpu can be in different logical GD-networks.

a) 1 cpu sends a message and up to 4 different cpu's can recieve the message.

b) 2 cpu's make up one GD-network. Both cpu's can send and recieve.

 

[JesperMP]

It does not sound so good with an extensive network based on MPI.
What CPUs are you using ?
The onboard MPI ports on the lower end S7-300 CPUs do not have galvanic isolation to the backplane, so the recommendation is that the entire MPI segment not exceed 50 meters. It is possible to split the segments by using repeaters.
The amount of traffic may also be a bit much for MPI at 187.5kbps.
Do you have 3 times S7 CPU plus MP277 (6 in all) ?
Or do you have 6 times S7 CPU plus MP277 (12 in all) ?
That you are using smartaccess on the MP277 panels to remotely operate each station is sensible enough. But putting everything into one network on the MPI side may be too excessive, both for the electrical connection, and the amaount of data to transfer.

With all the above being said, it should be possible to exchange data via X_PUT and X_GET. Maybe the problem you are encounting is too many open connections per CPU. You can check how many connections are available by monitoring the CPU online.

edit: I see from post 2, that the CPU type is 315-2DP. Is that 3 CPUs or 6 CPUs ?
With that hardware it is not easy to establish peer-to-peer connections between all the CPUs, except for via MPI.

 

[tulip]

I used 3 plc's and 3 hmi's.I used FB14 ''GET'' in and saw
ERROR=1,STATUS=1 Explanations:
Communications problems, for example:- Connection description not loaded (local or remote)- Connection interrupted (for example: cable, CPU off, CP in STOP mode)- Connection to partner not yet established- FB cannot be run on an S7-400-CPU- Also for S7-300:· Maximum number to parallel jobs/instances exceeded.I want to learn that another subject
.Is there any Master/slave organisation for mpi communication?

 

[JesperMP]

If you connect a PG to the MPI network, can you then find all the stations ?
Check online the number of available and free connections on all the CPUs.

 

[tulip]

Yes I saw all of them online.

 

[JesperMP]

And what about this: ?

Check online the number of available and free connections on all the CPUs.