What is the best method to communicate between two FP-2000's 700m apart?

[Geeth]

I wish to communicate between two FP-2000 modules separated by 700m. The constraint is that I want to use a 2 wire communication system. This makes RS-485 seem like the right choice.

Is it a valid structure to use 2 FP-1000's (connected to the FP-2000 through the RS-232 port) and communicate using RS-485?

Even if this is valid, it is still going to be a full-duplex (4-wire) solution! Can soemone help with any other alternative solution?

[Aaron_G]

RS-485 is suitable for your application as it offers a two-wire communication mode in which the transmit and receive wires are tied togther (the Rx+ and Tx+ are wired to each other as are the Rx- and Tx- signals).

The FP-1000's can be used to convert RS-232 to RS-485 but do not support two wire mode so they are unsuitable for this scenario. You can get RS-232 to RS-485 converters that will support 2-wire mode. Two wire mode does not allow for simultanous transmission and reception, so a protocol/handshaking method must be programmed in your LabVIEW code such that only one FP-20XX module tries to transmit at any given time.

Regards,
Aaron