Programming Siemens S7-300 over FO profibus


Thread Starter

Jan Nielsen

We are experiencing a strange problem with our little network of two S7-315-2DP CPU's. They are connected on a fiber optic Profibus DP network for data presentation on Siemens OP7 and TP27 panels, and for data exchange between CPU's.
We want to be able to connect remotely to both CPU's via telephone/modem, so we have connected one CPU to the modem with a TS adapter to the Profibus interface.
The data exchange between the CPU's is working well, but we cannot access the remote CPU for programming. The strange thing is that if we connect the two CPU's with standard profibus cable, there are no problems with programming.
Anyone out there who know about this kind of problem?

Daniel Chartier

Strange situation; the docs from Siemens (both for Teleservice and Routing Networks)claim that you can use either MPI or Profibus-DP interfaces on the CPUs for the Teleervice adapter to work. Have you tried plugging the TS adapter on the MPI interface of the CPUs? With this connection we have never experienced any (major)problem.
Are you using OLMs for the transfer of Profibus to FO?
Hope this helps,
Daniel Chartier
the TS adapter works fine on MPI, but we have not tried to route from MPI to Profibus to the other CPU.

Siemens suggested that on some CPU's there are no 24 V supply in the Profibus interface, but this is not the case here, as we can program a CPU directly via Profibus interface.

Also we have not tried to connect the CPU's over MPI. This would work fine I think, but we have to use Profibus because of future expansions. We are using OLM's, and this is actually the first problem I have encountered with these. They are otherwise of high quality and "just works".

Best regards
We use OLMs to convert copper sinec profibus cable to fiber optic and connect to remote i/o and s7-300 PLCs. We have a programming station which we use a CP5611 card I think it is to program/monitor the s7-300s remotely over profibus. You must setup this card in the PC you are using to program your PLC system, and then set the PG/PC interface, after setting any other additional COML S7 parameters within softnet.

Good luck!