I'd like to connect more than one RS232-device to the one RS232 being free
on my SBC.
If I used RS485 I had to use a special prototcol, which besides the data
containes the address of the slave device the master wants to speak to. No
problem on the master's side. But those devices are completely unaware of
anything other than one master connected to them. And as it is not possible
for me to change the software of those devices (to tell them to listen to an
address byte coming over a RS485 network), this solution seems to be ruled
At I found switchers being advertised, doing exactly what I
need. But guess what, they are built to be used with PCs: Large boxes, heavy
and - expensive. Nothing for my mobile robot.
There are ICs like the DS3695A from National Semiconductor, the MAX485 from
MAXIM etc. They all have pins to enable/disable their lines. But if I
understand it right these pins have to be set by the device hosting the
chip. Or could my master enable/disable the DS3695A of a slave thus
selecting it for communication? I guess, not.
Could I use a mux (or is it a demux?). Such ICs are used to get more I/Os
than are actually available. Probably not the right thing for this job, I
don't know. If it was that easy, the Internet wouldn't offer such large and
Any hints? Any pointer is appreciated.
Many thanks and kind regards
19 years ago