Siemens PLC communication with PC

I would like to test Siemens S7-CPU315DP to communicate with a PC, either via MPI or profibus protocol and enter through RS 2332 port in PC. Please suggest the communication parameter ( Send or receive data format) that I could use iby using VB or C++.
Thank you

Hello Teowk;
MPI and Profibus are both RS-485 protocols, so will will need a protocol converter to connect to a RS-232 port. Siemens of course has its PC-Adapter, but you can fnd other MPI adapters on the market. Note that a straight RS-485 to RS-232 converter, that you can find from B&B or other electronic manufacturers, will not work; there are conversion issues that are handled by the specialized modules.
Once you have the hardware issues under control, you have several choices:
- use an OPC client to connect to Siemens MPI/OPC server
- buy Siemens' Computing package, which has integrated libraries to link C code to MPI through OPC (Entry ID:1171633 o Siemens' webpge, www4.ad.siemens.de)
- use Siemens' Prodave MPI package for the Borland C++ compiler or VB(Entry ID:100831 in Siemens' webpage)
- look at other developper's code, such as Luca Gallina's runmode.com

Hope this helps,
Daniel Chartier

Siemens PLC and OPC

Dear Daniel,
Thank you for your help. Your first suggestion of OPC Client is new for me. Could you elaborate on how this communication can be done by using Visual Basic or Visual C++ ? I have a converter here which convert MPI to RS 232 serial port by Siemens. I think I will use this port for PC and PLC commmunication.

Thank you.

Siemens PLC and C++

Dear daniel,
I have just visited the web page and obtain useful information on the OPC Client. Thanks a lot. About the second ID, 100831, the web page failed to search this ID. Is this the right ID?
Thank you.
Best Regards,

Teo WK

Hello Teowk;
Glad you found information on the OPC Client and I hope yopu can use it in your program.
The ID:100831 seems to work;
here is an excerpt from that article:

Hope this helps,
Daniel Chartier

For simple application an MPI converter could be very expensive.

If you need to test one PLC programmed with Step 7 from Siemens you should think of testing one VIPA CPU. For nearly same price of one Siemens 315-2DP you can buy one VIPA 315-2AG10 with MPI, Profibus Master and Ethernet. You can also test MPI or Ethernet comunication with the VIPA OPC-Server (in demo mode can be used for 24h, rebooted and more 24...and so on...) and for OPC client I like to use the WinTech solution.

VIPA CPUs have one special MP2I port with RS485 and RS232 so you can make your comunication testes and also program it with Step 7 using a "normal" RS232 cable (no converter needd) and comunicate at 38400 baud. If you prefer ethernet, you can do the same but at 100Mbaud.