Rs-485 Problem

HI THERE,
I HAVE A CPU S7-200 AND A POWER MONITOR PM-600 (SQUARE-D) AND I WANT TO CONNECT THEM IN A SERIAL NETWROK TO A PC USING A PPI CABLE.
THE PROBLEM IS THAT I CAN'T MAKE THE POWER MONITOR COMMUNICATE WITH THE PLC OR THE CPU (COMMUNICATION IN MICROWIN DOES NOT DETECT ANYTHING WHEN ALL IS CONNECTED BYT DETECTS THE PLC WHEN CONNECTED ALONE).
THE PLC HAS AN ADDRESS=2 AND THE POWER MONITOR HAS AN ADDRESS=10.
I THINK THE PROBLEM IS IN THE CABLE WHICH CONNECTS THE CPU WITH THE POWER MONITOR. SO CAN ANYBODY TELL ME HOW DOES THE CABLE WORKS OR ANY OTHER SOLUTION FOR THE PROBLEM?
THANKS

I am lead to believe by one of my customers you require a co-processor card and some very expensive Siemens Modbus protocol software. Not 100% sure but that is what my customer tells me.

Hello AmazingAhmed;

The PPI cable is a converter from RS-232 to PPI (RS-485). If your power monitor is to be connected to RS-485, use Profibus cable and connectors or an MPI cable for short distances.
You do not give indications on the protocol used between the PLC and the power monitor. Is it Modbus RTU? If so, there is a Toolbox add-on to MicroWin that contains the code to setup the S7-200 as a Modbus master. If you use ASCII, you can check the Tips and Tricks for S7-200 (downloadable from Siemens' website) for freeport protocol implementation.
Hope this helps,
Daniel Chartier