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Mesut_yigit
Joined: 31 Jan 2005
Posts: 9
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 10 Mar 2005 19:39 Communication method for long distance 3coreelectrical cable |
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Hello
In my last project , I have to find a reasonable way to communicate 2 PIC devices in a 3 km distance. Communication rate can be as low as 115 Baud. The one pic will send a couple of values to other , uni directional communication scheme. The communication will be performed over an classical 3 core , 2.5 mm2 electric cable that does not used to carry electricity anymore. Because of the geographical conditions , I have no chance to replace that cable with a usual comm cable.
Could someone suggest a proper way ?
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flatulent
Joined: 19 Jul 2002
Posts: 4875
Helped: 324
Location: Middle Earth
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10 Mar 2005 21:21 Re: Communication method for long distance 3coreelectrical c |
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This looks like a job for very old telephone modem technology. Some of the original formats from 25+ years ago were 110 bits/sec to 300 bits/sec.
If you cannot find any hardware for this, you can make your own by using FSK on two carrier frequencies (one for each direction) that are well separated.
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gidimiz
Joined: 03 Feb 2005
Posts: 428
Helped: 77
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10 Mar 2005 22:04 Re: Communication method for long distance 3coreelectrical c |
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Hi,
Dont know what you have ( cable wise ), but there is an easy way:
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What is an RS-485 network? RS-485 allows multiple devices (up to 32) to communicate at half-duplex on a single pair of wires, plus a ground wire (more on that later), at distances up to 1200 meters (4000 feet). Both the length of the network and the number of nodes can easily be extended using a variety of repeater products on the market.
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More info on http://www.bb-elec.com/tech_articles/rs485_basics.asp
Its easy to implament with 1 IC that converts the UART into RS-485. Depands on how many wires you have, you can use Half Duplex, or Full Duplex.
More information you can find on google, or here if you ask for somehting specific.
Good luck.
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sraiderk
Joined: 09 Mar 2005
Posts: 40
Helped: 11
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11 Mar 2005 9:53 Re: Communication method for long distance 3coreelectrical c |
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| Ofcourse You can use modem to comunicate. You can use modem and control it by mcu. Then I think that it is ok.(no speed, no distance problem)
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