Communicate S7-200 with another S7-200

can someone tell me how to (if possible) to make a cable (peer-to-peer) so that I can exchange data, back and forth? by telling me the wire connections?

Since I'm gonna be doing this first time, please also advise if there are any cable length restrictions.

If its a special kinda cable, which cannot be made at site, please advise an order code so that I can order directly from Siemens.

Thanks

profibus cable

You can make a cable by connecting pin 3 to pin 3 and pin 8 to pin 8 of each CPU using a twisted pair cable.I would advice to connect also the screen of the cable to the metal part of the RS485 plug at one side.
The above is the cheap method to do it but if you want better protection of your CPU you can buy two profibus connectors which are not so expensive.These have some protection resistors inside which will protect the CPU port from spikes.

thanks geofra,

can you also suggest how I can connect more than two PLCs, altogether.

I think it gets complicated, when I tell you, I will need the other port free, coz I wanna connect a TD-200 to it, so all I can give you is one PPI port free!!

I am considering Profibus or Ethernet, but since there are only two values I need from the PLC (15 of them!!), and no other use, I feel hesitant to use an expensive means.

Profibus

I suggest you buy the profibus adaptors from SIEMNS for your application. There are two types of adaptors 6ES79720BA500XA0 ,6ES79720BB110XA0
One type of adaptor has a RS485 port which you can use to connect TD200 and also gives you the terminals to connect profibus.The other type does not have the RS485 port option. On each of these adaptors you have in/out terminals so you can expand your network up to 32 devices using twisted pair cable. Each PLC will have its own id.