adrian aslett wrote:
>
> I am looking for information or coding using the RS485 protocol.
>
> Can anyone provide me with information on this.

I am sorry to disappoint you, but RS485 is not a protocol. It is the
physical layer, such as RS232, RS422, optical cabling, coax.

RS485 is a way for serial communications on a two wire cable, where
shielding is not (or less) necessery.

The devices use a method of transmitting data that is highly insensitive
for external interference like magnetic fields.

For implementing RS485 within a PIC project, you'll have to know that
RS485 uses an external component like a SN75LBC179 for the job. You
cannot 'emulate' it with the PIC.

The question now is, does the RS485 bus one or more transmitters. If you
use just one transmitter, the job is easy. Set one transceiver (that's
what they're named) to Send, and the other to receive. Done.
If you have more tranmitting devices on the same set of wires, it gets
more complicated. You'll have to watch the state of the 'bus' to avoid
data collisions. If you want more explanation of this, let me hear.


CU,   Frank  (p.f.tamminga@hgt.nl)