Amplicon CP-102UF fibre-optic serial board, a universal PCI board with dual fibre-optic serial ports.

The CP-102UF is a smart Universal PCI board and is compatible with all popular operating systems. It provides 2 serial ports that each support data rates up to 921.6kbps. Because 3.3V and 5V PCI buses are supported, the CP-102UF can be installed in virtually any PC or server.
 
Using singlemode fibre, serial data transmission can be extended up to 40 km, exceeding the 15m limit for RS-232 and even the 1.2-km limit for RS-422/485. In many industrial applications, an even bigger benefit is that optical fibre isolates the data from dangerous increases in ground potential, ground loops, and electromagnetic radiation.

Using the CP-102UF, a PC can be included as a node in a fibre-optic ring that is formed with Moxa's TCF-142 serial-to-fibre converters. Each TCF-142 in the fibre optic ring can connect to a serial device with the potential to build large, highly-reliable networks of serial devices.
 
A simple DIP switch setting configures the CP-102UF to ''ring mode". When one node transmits a signal, the signal travels around the ring until it returns back to the transmitting unit, which then blocks the signal preventing messages from looping endlessly around the network.

More information: www.amplicon.co.uk