Re: [Gumstix-users] Chip that converts Gumstix line level to RS232/RS485 and/or RS422

[ken s. <ken...@gm...>]

On 10/19/06, Joe Thielen <jo...@jo...> wrote:

> When I plug it into Linux, it uses the pl2303 chip driver.  But I've
> never cracked open one of these things to see if it just has a pl2303
> chip in it, or if it has more circuitry for the RS485.  This box will do
> both, and works perfect.

The PL2303 handles the USB to async serial.
RS-232 requires an interface chip.
RS-485 requires a different interface chip.
The box you refer to must have both (in addition to the PL2303).

The gumstix just needs an appropriate interface chip for the signalling you want
to use. Try MAX3232 for RS232 and MAX3485 for RS485.
The datasheet will have an example circuit.

Regards,
Ken