Real RS-232 Cable Length Limit

[danielthb]

175 cable feet of STP between a PC comm port and the DCE--think it'll work at 9600, at 19.2k? I'm not looking for what the specs say but what your experiences are. Cut sheet for the cable says 40pF/ft @ 1.0 MHz.

Dan B

 

[itsmoked]

Sure.

Oh..
40pF/foot... That sucks.

Maybe not. If it doesn't, it's your crummy cable.

It's a hard call really as it also depends on your electrical environment. I would imagine 9600 would be dependable. Maybe 19.2k with good cable. In a benign place.

Hopefully you are driving the cable with nice levels not some laptop with +/- 3V levels.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[danw2]

I doubt there's a commercial cable for this service, so your're talking custom cable. That'll cost ? ?

If it's a dollar a foot plus connectors and labor, $200?

What about a couple 232/485 converters, one for each end, and 200' of twisted pair that you've already got lying around, instead? Far higher probability of it working.

Dan

 

[controlsdude]

If you use this cable spec you can get 500 ft distance. experienced it myself.

Black Box EDDC

but on the - side it is expensive.

 

[itsmoked]

controlsdude; You experienced it at what speed?

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[controlsdude]

I believe most of interfaces were at 9600, some were 19200, and never above that speed. bar code scanners usually char length= 20 to 50. sometimes scales, conv speed up to 550 fpm, gap between cases 12-15 inches.

 

[MikeHalloran]

I don't think you'll do 9600 at 175' over STP.

Current loop should work okay.



Mike Halloran
Pembroke Pines, FL, USA

 

[itsmoked]

Well Black box said 500ft.

http://www.blackbox.com/Catalog/Category.aspx?cid=45,85,790

They don't say at what baud rate. Might be 300. But I think 175ft is possible. I had about 120 feet that we used all the time for various serial endeavors at speeds up to 34,5k and I don't remember having any problems.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[controlsdude]

some applications that I did were up to 400 feet and at 9600 baud as far as I remember. It all depended on main panel location and scanner locations. This was with the black box eddc cable.