DB-9 cable length limit

Question

DB-9 cable length limit

mattski72 (Industrial)

(OP)

15 Aug 11 11:55

What is it? I need a cable run of around 60 to 80 ft. Will DB-9 do the job or should I convert to something else and adapt at the components? Thanks in advance.

IRstuff (Aerospace) · Answer 1 · 2011-08-15 12:00:39

DB-9 is a connector specification, PERIOD. How long the cable can be is a function of what signals you're running and how you make the cable.

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mattski72 (Industrial) · Answer 2 · 2011-08-15 12:16:44

Sorry.  I am obviously not the expert here.  Feel free to humiliate me if neccessary, just teach while you do it.

Down to the nitty-gritty.  I have to move a 900 mhtz antena further away from my building in order to get a good reception.  But I cannot extend the coax cable as that screws up the reception also.  Soooo....I need to run cable fromm the antena base or converter (located a the antena) to the PC (about 80 ft away).  It has to be DB-9 connectors or adaptable to that.

The question: how far can I go using the standard RS 232 cable and not suffer.  This is low baud rate stuff

Your replies are greatly apprciated.

IRstuff (Aerospace) · Answer 3 · 2011-08-15 12:38:29

"This is low baud rate stuff"

900 MHz is NOT low baud rate, and if that's what you're trying to transmit on this "RS232 cable," then I would guess about a foot or less.

Isn't the rest of your antenna cable coax? If you can't get it to work, then you're doing something wrong, and you need to get someone with antenna/RF knowledge to help you.

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robertjo24 (Industrial) · Answer 4 · 2011-08-15 17:58:41

I assume you are remoting data of some sort through a 900 Mhz radio? What is the baud rate of the RS-232 data? The transmission distance for RS-232 is dependent upon many factors, but the data rate and cable type are the two most important. The RS-232 "standard" lists the maximum effective transmission distance of 50', but that is at 20Mhz. If the data rate goes down, the distance goes up. Also, use the lowest capacitance cable, i.e the smallest diameter cable. Using a low capacitance cable and a slower baud you can take RS-232 data pretty far. 80' at 9800 baud should be no problem at all.

robertjo24 (Industrial) · Answer 5 · 2011-08-15 18:07:31

Also...there are port powered RS-232 to RS-485 converters that will extend this connectivity out several thousands of feet.

This will allow you to run 100' with a higher serial baud rate.

You can get these devices from places like B&B Electronics (http://www.bb-elec.com/Subcategory.asp?SubCategoryId=12&Trail=2&TrailType=Top) or Black Box.

IRstuff (Aerospace) · Answer 6 · 2011-08-15 18:17:40

My bad, I misread your post, running serial at low baud rate at 100 ft should not be a problem.

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DB-9 cable length limit