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Old 10-29-2004, 12:02 PM   #1
Onyx^
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Linux and RS485 question?


Hi there,

Does Linux support rs-485 (specifically single-pair rs485)?

If I have an rs-485 device on ttyS3 am I able to control it through Linux or would I have to write my own drivers?

Thanks in advance.
 
Old 10-29-2004, 01:47 PM   #2
michaelk
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The short answer is yes.

RS-485 is an electrical and not a protocol specification.

If you have a RS-485 to RS-232 converter connected to the serial port or a RS-485 PCI card your set. You can talk to the device using minicom or any other serial communication program. So no special driver is required but you do need to know the device's command structure.

Last edited by michaelk; 10-29-2004 at 01:50 PM.
 
Old 02-13-2006, 09:06 AM   #3
mishal4
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can I a little expand question.
how i can use several devices on one rs485 port? (up to 32 devices) I can just use ttyX to send or recive for only device as i understand - were i can at least to read "fucking manual"?

Last edited by mishal4; 02-13-2006 at 09:13 AM.
 
Old 02-13-2006, 09:27 AM   #4
wraithe
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rs - 485 basic is 32 nodes but can be expanded to 1024 nodes. rs 485 is also a polling type network not event driven so all nodes are polled.. best info i've found was on a berkley site (not got any addresses sorry) but if you look up lenz under model train DCC(digital command control) they actually use rs 485 for there controller bus and have some good links. I haven't used them for a while so sorry can't give you directions..
 
Old 02-13-2006, 09:43 AM   #5
michaelk
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mishal4
Here is a basic tutorial.
http://www.circuitcellar.com/library...0799/index.asp

Assuming everything is connected to the same serial port using ttyx can not be used to address a single device.
 
Old 02-13-2006, 10:33 AM   #6
mishal4
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thank's all for the answers - i familiar with electrical questions. on a simple processors such networks was build.
but i need linux operated eia-485 network.
i need some tutorial how to write a program for linux who can transmit data to the selected node and recive data from it.
i can do it on the low level - but i need a operating system point of view.
thanks
 
Old 02-13-2006, 11:54 AM   #7
michaelk
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Does your network use 9-bit mode? I haven't found a lot of information on how to do this in software since the PC uart does not have this capability built in.

Does not provide a lot of help.
http://www.elecdesign.com/Articles/A...6245/6245.html

Last edited by michaelk; 02-13-2006 at 07:12 PM.
 
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Old 02-13-2006, 10:42 PM   #8
michaelk
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Here is something that might be useful
http://rs485.bocc.de/
 
  


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