So you're interested in building a COMM-Link board. To start with you're going to need to build a board from scratch (design a board and have a PCB made or build a prototype on perf board) or buy a board and modifiy it you your needs. I won't suggest ways to build boards from scratch here. but I hope to have another article on building boards from scratch as it requires some advanced techniques which most likely means you don't need this kind of tutorial. Ready made blanks are available from places like microEngineering Labs, Inc. The Microchip PIC 16F628 or PIC 16F877 is a good chip to start with. If you're buying a ready made board Futurelec is a good choice. The P89C51, T89C51, ATMega or the PIC16F877 board is a good place to start. Just make sure that you purchase any of the extra chips you might need (such as the RS485 chip).
To start with a RS232 port is acceptable, as the HCS really doesn't know whether it's communicating over RS232 or RS485. Later you'll need the RS485 chip for hooking up to the HCS. The HCS is built for 2 wire RS485 (half duplex communication). The remotes are wait to be polled by the SC whic is in control of who gets to speak and when. Addition items needs for the intial testing are LEDs, resistors, and push button switches. Later we may tackle adding an X10 interface which only requires 2 pull up resistors and an RJ11 jack.
For further info email me at: firstname.lastname@example.org.