[?]: Profibus DP Communication for two S7-300 masters

[slwasm]

I have system with two s7-300 cpu and three analizators SIMEAS.
The first CPU read analizators.
Second CPU read data from first CPU.
All devices work on the one bus of Profibus DP.
Please, help me.
I need sample for communication with two masters of S7-300.
May be, I shall solve this problem with DP/DP Coupler.
Thanks.

[scozans]

You don't need a DP/DP coupler to exchange data between 2 masters - you will only spend more money just to realize that you are to face the same problem as before all over again, maybe another problem with that one. Actually in the HWConfig you can declare the PI/PQ that you need to exchange aside from the SFC/SFB from the library, just pick the right one for your needs.

[Umencho]

You don't need a DP/DP coupler to exchange data between 2 masters

Actually in the HWConfig you can declare the PI/PQ that you need to exchange aside from the SFC/SFB from the library, just pick the right one for your needs.

Hello

Very interesting opinion. Can you give us more information about this way? I can't find example but hope this links can help you a little.

Configuration of the I/O Data on DP/DP Coupler
http://support.automation.siemens.com/W ... n/22809787

What are the special features of input/output addressing with the DP/DP coupler? + Manual DP/DP Coupler you can find link inside
http://support.automation.siemens.com/W ... n/22809309

regards

[Umencho]

You don't need a DP/DP coupler to exchange data between 2 masters - .....
....... from the SFC/SFB from the library, just pick the right one for your needs.

Hello

This is true if we speak for MPI (Multi-Point Interface) connection between this 2 masters. BUT:

System functions (SFCs) are used to this purpose.
These SFCs perform the following tasks:
● Reading and writing access to data in the SIMATIC S7 and C7 controllers
● Transferring small amounts of data through an MPI subnet to another S7 station (S7 controller, panel or PC)
The maximum amount of data that can be transferred is 76 bytes.
Communication with stations in other subnets is not possible with the SFCs for S7 basic communication. Modules can be addressed in the local station or in the MPI subnet:
● SFCs for exchanging data between an S7 CPU and other modules with communication functionality, if the communication partners belong to the same S7 station. These SFCs are identified by a preceding "I" for internal.
– I_GET (SFC 72)
– I_PUT (SFC 73)
● SFCs for echanging data between an S7 CPU and other modules with communication functionality, if the communication partners are connected to a common MPI subnet. These SFCs are identified by a preceding "X" for external.
– X_SEND (SFC 65)
– X_RCV (SFC 66)
– X_GET (SFC 67)
– X_PUT (SFC 68)
The connection is not configured, but is rather established explicitly when the SFC is called up by the user program. After the SFC has finished transferring the data, the connection either remains established or is terminated, depending on the parameterization. If a connection cannot be established, the corresponding job is not sent. At any one time, a maximum of one connection is possible to a communication partner.
The number of communication partners that can be reached one after the other is not restricted by the connection resources available.
More information there: http://support.automation.siemens.com/W ... en/1254686

regards