Hi Nihat,

You can also do it the hard way, by using a microprocessor to interface with the PC. The messages from the PC are prefixed with an address character, which tells the micro which RS232 driver/receiver pair to use (only 1 channel active at once here). I built a deal like this a number of years ago. The client had to interface a PC with 12 devices running at 1200 Bd, echoing every character as a check. He put 12 Tandy 1000's in a rack to handle the different communication rates, bufferng & protocol, then I added the switch. I told him after that I could have handled the whole thing with my micro!
Ah yes, & my box included the 12 current-loop drivers.

Regards,

Richard