MPI Messaging

Hi guys.. I am new in the world of Siemens, so please bear with me. I have 2 CPU314-2 PTP Processors that are connected via MPI. I need to send data from one plc to the other. What block would i use to accomplish this?

For MPI, use X_PUT and X_GET.

Excellent... looks like its what i need, But how do I tell the block how much data to send or recieve?

You have to specify where the data has to be retrieved from in the source PLC and where it has to be stored in the target PLC by means of ANY pointers.
An ANY pointer can point to any type of variable and also informs the number of variables to send.
I dont have an example right here and now. Tro to check the online help about ANY pointers.

With MPI you can use global data to send data from plc to plc. We use this a lot (replacing the relay communication between plc's which we used in the past). Most of the time we just send 1 or 2 words.
There is no need to program the communication protocol just set up a connection matrix/interface.

Thanks Werner. I got into the matrix in netpro, but i cannot seem to do anything, any words of wisdom?

Out of my head:

The plc's have to be connected to the MPI network. (Hardware configuration properties of the plc. Connected to network must be yes).

All plc's must have unique MPI address. Save and compile all hardware configurations.

In the s7 manager right click on the MPI connection and select define global data. Now you you see the matrix. Add plc's to the coloms. (Click at the top of the first colom, and select add/select plc)

When this is done you can start to define the interface.

Example:


A cell in the matrix can be receiving or sending data. In this example it might be that CPU1 is sending DB20.DBW10 and CPU2 is receiving this information in DB21.DBW2

When finished defining the matrix you have to compile it. (Compile twice, in the right bottom corner of the screen you will see phase 1 after compiling the first time and phase 2 after compiling the second time. When compiling twice (phase 2) then the configuration is stored in the SDB and on eprom/flash memory card) Then download this global data definition to all plc's using the download button in this configurator.

We use puls bits in all plc's to check wether the connection is still "alive".

I don't have my computer with me so sorry if I made some mistakes, but this is the general idee of setting up a global data connection.