Siemens Step7 w/315-2 CPU

I have a Siemens system with a 315-2 CPU and 4 nodes. One of these nodes is a slave 115-7 CPU. The others are remote racks with normal I/O. The 115-7 is the last node on the profibus net.

If I connect at the last node (piggyback profibus connector) with my laptop I have access to the entire net, however, if i connect ANOTHER laptop (two total) via profibus, either at the ending node or any other location in the daisy chain, i immediately get a "BF Fault."

I have checked to make sure that the two interface modules (5511 and 5512) do not have conflicting node addresses and that neither conflicts with any of the system node addresses.



Should I be able to connect the two laptops? Can they be used for programming at the same time? Is there a method I should follow to get two on the system?

Hope everyone has a great Turkey Day!!!!


Thanks for the input!
JiNCs

What bus speed are you running at ?
At 187.5k you can do almost anything without problems.
At 1.5M it is more sensitive.
At 12M, as far as I understand, you will get a BF at the slightest hickup (which is why I dont use 12M ).

Thanks Jespser!

Sorry for the late response but at an actual startup.

We are currently running at 1.5M. I think we have enough I/O and instances that require a fairly quick response that I would be afraid to try lowering the bus speed to 187.5k.

Currently we decided to share one PC. I guess we can try one PC on the MPI connection at the 315 processor and the other on Profibus.





Couple of easy questions . . . MPI and DP are acronyms for what???


Thanks again Jeesper!!!


JiNCs


By-the-by . . . I noticed your signature icon. If your can get your hands on some, try a Samuel Adams Boston Lager or their Holiday Porter. Would love to hear what you think!

Hello
i think you can connect two laptops on the same network at two other places...
but make sure from PG/PC interface->>under proerties of 5512MPI that u must not be a master for both laptops...so try to uncheck for one laptop ....
i think u r goig as master from both and getting the "BF"

thanks and all the best.

Thanks rahilansari,

Just checked that setting on my laptop and I have it set for 5512(Profibus) and it is not selected as the master.
I will have to check the other laptop tomorrow morning.

I will aslo look into if the selection should work with 5512(Profibus) or 5512(MPI) . . .


Thanks
JiNCs

yes go with 5512(MPI) and see.

JiNCs said:

Couple of easy questions . . . MPI and DP are acronyms for what???

JiNCs

Click to expand...

Hello JiNCs;

MPI is an acronym for Multi-Purpose interface, a subset of Profibus-DP, generally limited to 187,5 kB, used between a PC (Step 7)to program the S7-300/400 PLCs, to exchange data peer-to-peer between these PLCs, or to network S7-200 CPUs as slaves to S7-300/400 PLCs.

DP is one of the flavours of Profibus; Profibus-DP stands for Process FieldBus-Decentralized Periphery, or in everyday language, Remote-I/O. It is designed for high-speed (up to 12 MB), small packet exchanges between a master (the CPU, generally) and interface modules in the field.

Hope this helps,
Daniel Chartier