From: "Frank Bemelman"
Subject: Re: RS485 help #2
Date: Fri, 25 Oct 2002 21:46:46 +0200
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Organization: EuroNet Internet
NNTP-Posting-Date: 25 Oct 2002 19:48:25 GMT
"EBG" schreef in bericht
> Forget about RS485 for a minute.
> What I'm asking is this...
> What if I simply take the RS232 out of the PIC and drive two optos, one
> an inverted signal, run twisted pair
> (without a shield) and receive the data on another pair of optos (outputs
> xmtr optos drive the led's of the rcvr optos).....have the rcvr optos
> outputs feed an op amp and
> end up with my data?
First of all, the PIC does not do RS232 out, it is simply serial data
out, 0-5V levels. Can you scribble down that 'simply RS232' idea?
If you want to send & receive to multiple slaves, you will discover
an interesting problem. Sending & receiving will have to take place
over the same wires, bidrectionally, so you have transmitters on both
(all) ends. Unless you want one-way communication only, which simplifies
> 1200 baud or even lower just to control some switching.....
> my goal at this point is to try and reduce/eliminate EMI emmision from my
> twisted pair (compared to unbalanced
At 1200 baud, you can drive the opto real slow, no EMI emmision to worry
about at all!
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