Good day Picers
What is the cheapest way to communicate between pics at a distance of 100 meters?
Thank you!
Cheapest way to communicate
Good day Picers
What is the cheapest way to communicate between pics at a distance of 100 meters?
Thank you!
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Pics get pretty expensive once they let out a puff or two of smoke...
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433 Mhz modules
There are plenty of 433 Mhz modules you can use for this. Pick the right one and you can have up to 500m.
One way or 2 way communication?
Cable? fiber optics...
Usually the communication part is not the problem, it is to provide power to all units without having to change batteries every day.
/me
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Is wireless cheaper than RS485?
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Depends on what type of cable you run...........
http://www.scalerobotics.com
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But that might be a one-time expense. The OP really hasn't provided sufficient detail. Even Melanie's educated string probably cannot hazard an educated guess. What's the duration of the communications link? Is it one-to-one or one-to-many? What type of messages? What's the terrain? Is the path horizontal or vertical? Is it level or does it span a canyon? How can a wire be routed? Stapled to tree trunks or utility poles, buried in a trench? Must it be taut or can it sag? Etc., etc.,...Originally Posted by tenaja
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it is a 24/7 communication link, every second.What's the duration of the communications link?
one-to-manyIs it one-to-one or one-to-many?
short, status monitoringWhat type of messages?
Horizontal, maximum of 1 meter difference in elevationWhat's the terrain?
Buried in a trenchStapled to tree trunks or utility poles, buried in a trench?
Can be sagMust it be taut or can it sag?
Thank you!!
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Probably the cheapest solution would be a 20 ma current loop circuit. 1 transistor (PN2222A), 1 opto-coupler (we use a 4n26) and a few resistors and you are set. I think I remember something about that being good for around 2000 feet, especially if you can go with a lower baud rate. Having said that, I would probably still go with RS422/485 just because it is more of a standard these days.
David
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If you have to have a two-way communication with more than one node, I think RS-485 is the best choice. Two way wireless gets complcated and expensive rather quickly. Also, most jurisdictions have limts on how often a wireless node can transmit. B&B Electronics has an excellent whitepaper on RS-485.
Last edited by dhouston; - 18th May 2009 at 21:49. Reason: added the wireless time limits
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laser pointers might work
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