RS485 info

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As we seem to repeat a lot of stuff regarding RS485 I thought it may be a good idea to make up a sticky with some information that prospective users may chew on.

As RS485 is an ELECTRICAL standard the info here is not dealing with software at present, maybe we can move the thread elsewhere in the future and add simple RS485 type code.

This link was posted by Brian Fairchild

Removed dead link 16/12/2106 http : // www .lvr. com/rs-485_circuits.htm

 

I'm adding a couple of PDFs which should be able to be posted without infringing any copyrights. If you feel that some should not be posted I will remove it/them.

Attachment(s): 

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

Last Edited: Thu. Dec 15, 2016 - 06:30 PM
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thank you interesting..
Thierry

Thierry Pottier

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And the wikki article is http://en.wikipedia.org/wiki/RS-485

It's a fast, pretty long distance multidrop wired communication system. Distances up to 1200 meters and speeds up to 35M bits per second.

Bits per second * meters should not exceed 10^8.

274,207,281-1 The largest known Mersenne Prime

 

"Head the warning. Avoid strong drink. It will make you shoot at politicians' -and miss."  -- B.Franklin.

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Excellent idea John!
You might want to put a sticky in the AVR forum as a link to this sticky as it is asked about quite a bit there if you have not already.

Once again, great thought.

If you want a career with a known path - become an undertaker. Dead people don't sue! - Kartman

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB user

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All the knowledgeable people know about the thread so that they can point newbees to it. :-)

A while ago I had in mind to post some MPCM code based on the "famous" Ampertronics' protocol but then my mind got distracted... :roll:

I had started an AS4 C project and the intention was to port the same code to ICC and CVAVR and of course have an assembler version too, now I'm thinking that an Xmega version would also be good but I haven't got a ROUND TUIT.

If I get one of those maybe the whole thread can go to Atmel spaces or not....

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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No, all the knowledgeable people will tell newbees to search for it, so that any search for RS485, RS-485, TIA458 or TIA-458 will turn up 153 threads saying to use search.

(Mainly posted to be sure this thread comes up when somebody does search.)

274,207,281-1 The largest known Mersenne Prime

 

"Head the warning. Avoid strong drink. It will make you shoot at politicians' -and miss."  -- B.Franklin.

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RS-422 uses the same drivers over two pairs, if you want full duplex. Of course you lose the multi-point bit, then... (can still have many receivers, though).

 

It's handy if you want a mile long serial link. normal code for 232 is the same, only thing changed is electrical interface in this case.

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You may also use Manchester encoding like Ethernet, and pulse transformers in middle to avoid ground issues, interface to hardware connected to mains, etc.

 

while(!solution) {patience--;}

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Here's an excellent article from Circuit Cellar by Jan Axelson.  I've used his her 555 pulse stretcher for automatic DE enable a few times with great success.

 

 

Attachment(s): 

Cheers,

Tom

Last Edited: Fri. Nov 7, 2014 - 04:35 PM
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tblough wrote:

article from Circuit Cellar by Jan Axelson.  I've used his 555 pulse stretcher.....

 

That would be Janet Louise Axelson,  no doubt.

http://en.wikipedia.org/wiki/Jan_Axelson

 

If only her parents named her Mary, there would be no confusion.smiley

Last Edited: Fri. Nov 7, 2014 - 04:32 PM
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Thanks so much for material, I spent last week on RS485 for a new project