Profibus communication between 315-2DP PLC 's

[Leonardo]

I would like to establish a communication between 3, S7-300 315-2DP PLC, using the internal DP port.

PLC 1 has to read 20 words out of PLC 2 and 20 words out of PLC3.
And PLC 1 has to write 5 words to PLC 2 and 5 words to PLC3

I was thinking to make a master/slave communication (PLC1=master, PLC2 and PLC3=slave) and to use the functions PUT en GET (FB14/FB15)

I looked on the Siemens support site but could not found a useful example. Only some information on some manuals, but unfortunately, not sufficient for me….
Could somebody help me?

 

[dchartier]

Hello Leonardo;
I know there used to be some documents on setting up a 315-2DP as slave to a315-2DP master on Siemens, website, but I could not find them this morning. Please bear with me as I will try to describe briefly the seqwuence:

1) Make sure all 3 CPUs are in the same project. Create them if you have no progamming done, copy and paste them from their seperate projects to a new central project if they already exist (you will need to reorganize the MPI addresses of the CPUs in this case).

2) start with PLC#2 one of the slaves); go to HarwareConfig, click on the DP extension on the CPU, opebn the Mode tab anmd select DP-Slave; open the Configuration tab. This is where you prepare the data exchanges betwenn master and slave. Start with Adding an Output module(from slave to master).; make it 20 words long, with UNIT consistency (that way you will be able to access them directly in the master, without copmm functions). You need to specify output addresses (QWx) available on the slave, and input addresse (IWx) available on the master. Next, setup an Input module (from master to slave), 5 words long, unit consistency, and specify avaliable addresses. Save and compile.

3) do the same on PLC#3; choose addresses on the master that do not conflict with those chosen previously.

4) Go to HardwareConfig for the master PLC#1; if you open the Hardware catalog, under Previously configured stations, you will find generic S7-31x slaves; drag 2 of them to the master Profibus network, and select your configured PLCs #2 and #3; give the slaves an adequate Profibus address; Couple the slaves to the master. Save, compile, download the hardware configuration to each CPU.

5) Make sure the data you want to exchange is directed to the addresses you have reserved in each CPU (Move instruction). Since trhe data consistency has beed chosen by unit, you can acces the data in the master by Byte, Word or DWord format without using communication functions.

Hope this helps,
Daniel Chartier