Communications between CPU315 and CPU314?

[Guest hurler]

Hi, I was wondering is it possible for a Siemens CPU315-2DP and a CPU314 (using a Profibus Card CP342-5) to communicate with each other on a Profibus network. Would anyone know of a Manual or link that would explain how or the reasons why not. Appreciate any feedback on this. Thanks

[Klaus 0]

Yes its possible. The easiest way is if you can use one of the cpu's as a slave.Then all you have to do is to insert the slave cpu in the masters Hwconfig. If you want to use master master communication it gets a little trickier. Then the first thing you have to do is set up a communication link in Netpro between the two units and the choose which communicationblocks you should use. Siemens has diffrent communication fb's "UsendUSEND(SFB 8)/URCV(SFB 9) BSEND(SFB 12)/BRCV(SFB 13) PUT(SFB 15)/GET(SFB 14)" read the helpfiles and see which is best for your aplication.

[Guest hurler]

Hi Klaus, thanks for your answer. On the original Profibus Network they'd set up the CPU315-2DP and the CPU314 on the same line both as masters controlling their own slaves but they never communicated between each other. From your previous mail I take it that I can get the two Masters to communicate directly with each other. "Then the first thing you have to do is set up a communication link in Netpro between the two units" Is the communication link the Graphical Profibus Network line in Netpro or are you referring to something else within the configuration? The CPU315-2DP Master communicate with it's slaves using the SFC14 and SFC15, the read and write commands while the CPU314 uses FC1 and FC2 to read and write to the CP. Can these be used or do the blocks you mentioned specialise in this type of data transfer. Eitherway I'll read the help files. Just on this subject if I installed another master from another brand say Mitsubishi, Omron etc can they be shown in Netpro and could they communicate directly? Again, thanks for taking the time on my previous query.

[Klaus 0]

No i'm pretty sure that you cant use SFC14,15 FC1,2 they are for communicating with profibus slaves. I checked the cp that you mentioned not all the versions can handle S7 communication between them. Open Netpro and select the on of the cpu's and choose "insert new connection". Choose S7 communication and select the other Cpu as the communication partner if this dosent work choose the other cpu and try the same thing. If this works you can use any of this blocks to communicate UsendUSEND(SFB 8)/URCV(SFB 9) BSEND(SFB 12)/BRCV(SFB 13) PUT(SFB 15)/GET(SFB 14). If you are unlucky setting up the connection in Netpro try Siemens hotline and they can tell you if communication between your units is possible. I taught you always could do master/master communication but i might be wrong. I always succeded but i mostly work with 400 cpu's and they are better on communicating. If you manage to set up the connection i could point you in the right direction on how to use the blocks. Regarding communication to other Plc brands you could insert connection to unknown units in Netpro but then i think that both units have to suport standard profibus communication FMS or FDL but again im not sure since i never done this.

[Guest hurler]

Hi Klaus, just for your information and anyone else interested. Found that there is actually a difference between S7-400 to S7-300 S7 communication. In the S7-400 family, you may utilize all interfaces i.e. MPI, DP, PROFIBUS, or Ethernet by means of S7 communication and the appropriate SFBs. However, at the S7-300 family, S7 communication may only be done via CPs, i.e.CP342-5DA02, CP343-1EX11 and so on, not via integrates interfaces like MPI,or DP. The CPU314's Masters can communicate directly with the FDL Connection. Thanks for all your help

[Guest JRW]

How much infomation (bytes) do you have to pass back and forth?? Why dont you just cable the MPI ports together and use global transfer or use XGET/XPUT. Jay

[Guest -User-]

Another possibility is use MPI global data send <--> receive words or bytes. Regards by -User-