Re: specifying Really Long serial cable

From: Guy Macon (http://www.guymacon.com)
Date: 10/18/04 

Date: Mon, 18 Oct 2004 06:43:57 +0000

Andrey <a8421@intergate.bc.ca> says...

>what would be wise recommendations for 100 ft long Serial cable.
>
>should it be shielded or not? (from interference point of view it should.
>But capacitance per length will go up. ??)
>
>Is there any reason not to use heavier gauge wires?
>
>What would be good cable for extended temperature range (-40C to +70C) and
>outsides (Sun, rain included)

What baud rate? TXD and RXD only, or handshaking?

Cat5 outdoor cable will handle the weather just fine and makes a fine
RS232 cable.

You can put the cable inside a PVC pipe or inside a high-quality
garden hose for protection against weather or physical damage.
Better yet would be a grounded metal pipe.

Interference won't be a big problem. Ground currents might be.
How sure are you that there isn't a voltage between the grounds
at the two ends?

What I would be concerned about most would be lighning strikes.
Do you have a plan to protect your equipment?

You really should consider putting optically Isolated RS-232 to
RS-422/485 Converters on both ends. Start here:
http://www.bb-elec.com/technical_library.asp
http://www.bb-elec.com/product_family.asp?familyid=14 

-- 
Guy Macon <http://www.guymacon.com>

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