Wiring terminals 300 ft. from the computer

[Jeff Johnson]

In <11774 at bsu-cs.bsu.edu> jennifer at bsu-cs.bsu.edu (Jennifer Freeman) writes:

>A company I am doing some work at needs to do some office rearanging as they
>are rapidly filling up the space they have.   They are also about to get a
>multi-user Unix Box running on a 386 or a 486.  One of the proposals is to
>locate the computer about 300 feet away from where the bulk (10-14)
>of the terminals will be.
>What type of wiring would be needed for this?  Would shielded be
>good enough?  Would some kind of line boosters be needed?  We have some people
>with knowledge of micros, but not in wiring multi-user systems.  Any suggestions
>things to look out for,  tips etc would be much apriciated.

The RS-232C standard (oxymoron?) limits the length of the cable to 50
feet.  However, I have installed cables up to 250 feet with only minor
noise problems.  (We had an AM radio station transmitter 1/2 mile away
and if the shielding wasn't grounded properly the wire acted like an
antenna.  It was very noticeable on our Merlin phone system cables that
ran parallel to the serial cables.)

We also ran a line about 500 feet using a passive modem from Black Box. 
We always had lots of trouble with this one at 9600 baud.  It had a
tendency of hanging the serial port or crashing the board.  It worked
better at 2400 or 4800 baud. 

I would suggest using 8-wire shielded twisted-pair and make sure you
ground the shielding and pick complimentary wires for the twisted-pairs.
Unless you have a very noisy environment or poor line drivers, it should
work. 


You could also look into fiber-optics.

--
Jeff Johnson			10926 Jollyville Rd #1420
Computer Consultant		Austin, TX  78759  (512) 343 0675
Email -> uunet!cs.utexas.edu!ibmchs!auschs!marichal.austin.ibm.com!jeff
Disclaimer: "My views and opinions do not reflect those of IBM"