RS232-Rs485 / PPI - S7-200 and WinCC v6

Hello.

I have successfully established connection via RS232/PPI between a WinCC6 PC and an S7-200 Device. All data are being read and the visuals and tags are being updated. I then replaced the dedicated line with an RF Transceiver at each end. I connected an RF Transceiver to the PC and then connected the other RF Transceiver to the RS232/RS485 - PPI convertor. When activating the project, the RF at the WinCC side transmits fine... however the RF at the S7-200 side is not receiving nor sending anything.. the Tx and Rx leds in the PPI convertor are not blinking.. knowing that the baud rate and all other configuration properties are set properly.
Why is this happening? is there a difference between Normal RS232 and RS232/PPI ? please help.

Regards,
Y. A.

Have you tried programming with the RF unit? Can you see the S7-200 at all?

Have you used gender benders? Is it possible that there is a cross over issue...Tx to Tx instead of Tx to Rx etc.

Just some thoughts.

Hi
Yes i have tried programming the PLC using RF. I was able to see the PLC, and it was able to reply to me. I have used a VB.net application to be able to monitor and control the PLC though the usage of RF transceivers. I have connected RF transceivers to both ends (PC and PLC), and all worked well. But when it came to WinCC, it was not able to perform any operation.

PPI isn`t possible trough RF unless the client (transmitter) supports larger timeouts (like Microwin) and the RF modems are intelligent (know the PPI protocol and able to buffer the frames).
I don`t know any RF which has this capabilities, you could try to test some one which supports Profibus, maybe it works.

Further, i don`t think that WinCC supports larger timeouts,
like Microwin.

So as i mentioned in another thread before, a RF connection to WinCC should be only possible trough Modbus.