Hi Guys,

Does anybody know the maximum distance RS232 can be sent down a cat5/6 cable before it becomes degraded over the length ? Is there also a maximum distance IR can be sent down a cat5/6 ?
Is there anything that can be added into the cable like a repeater or booster for either RS232 or IR to send it a longer distance ?

Many Thanks For Any Replies
S

50 feet for RS-232. This might be an old spec that was created before Cat5 was being used for it though. You might be able to double that using Cat5. With IR i have seen passive baluns with IR connections that say 1000' max distance so even if you cut that in half your looking at 500'. I have a few projects with IR being sent over Cat5 as far as 200'.

Whats the application? Crestron has room solution boxes that have IR and RS-232 connections on them that let you use Cresnet to wire back to the head end. Just Add Power HDMI over IP has an IR port also. Products like this allow you to circumvent the spec.

thanks for your reply,

my main application is using a RTI xp8, for possible control of local zone amplifiers with RS232 or IR, when I use our HDMI switchers we have IR pass through down the cat5 which is useful but was wondering if i was to attach an eye to cat5 how far would it travel. But i would rather use RS232 and thought it would travel quite far down a cat5 but i seem to be wrong about that, I thought i also heard that the length also depends on the baud rate, can anyone confirm this ?

S.

 correct, the lower the baud rate, the more reliable the data transmission will be over long distances.

39cent, why would be any different because of using a cat5 cable? One is the spec. of the protocol, that states to which distance it must work perfectly, and another thing is the actual usage.

The answer, pretty long distance. And if it's too little, grab a 232-422-232 converter, (232 and 422 are not too much different), then you're ok for 4000'. One good trick would also be to balance the rs-232 communication, just put 2 transformers 1:1 on each side, and run the balanced signals in a twisted wire pair cable (cat5), in the same twisted wire. Should lenghten the distance of 232, the problem might then be the MAX-232 IC to drive a long line like this (and transformer), but there should not be too much problems.

I don't know why it would be any different. I just know that 50' is the spec that i have always heard/seen/read and most serial cables are stranded "computer" cable. I know i cant pass HD over that type of cable but i can over Cat5. Obviously this is an assumption on my part that i am basing on my experience with a video signal and thats why i said you might be able to get further with Cat5.

Yes in the standard is specified 50'. The passing of the HD, were you trying with the HDMI? HDMI needs twisted pairs to work correctly, while standard computer serial cables don't have TP's (lower quality, cheaper to make) and that's probably the problem. But as I said before the standars (which is very old) defines just the min. distance that the communication has to work. Of course with the advancements with technology, better driver IC's etc, that number is no longer quite right, so is safe to assume that a bigger distance is possible. Once I tried it over 200m of cat5 (not layed down, just in a box) and there were no problems, just the propagation of the signal took a little more, so if you have 2 way communication, leave more time to get the acknowledgement from the controlled device.

The cat5 is a wonderfull cable, so cheap for so many wires. But it's not the purest copper, so special cables ment for industrial control might be a better choice sometimes. The rs-232 is not a symmetric signal (or balanced) so it doesn't really need a twisted pair, just 2 wires and you're set. Of course it's best if the 2 wires have the right impedance/m, but it's usually not a big issue.

No, component. It worked at one location where the cable was about 50' but the longer runs would not pass component video. This was at a project where there wasn't anyway to get new wire to a large touchpanel and the client wanted to connect component video to it. The original installation company ran cable thats jacket said "computer cable" and nothing more. They were using it for RS-232. In the same house we had one 17" panel located 100' or so away and there was an extra Cat5. I was able to use it for component video without baluns.

Interesting info, thank you. With analog video is like this, the impedance of the cable matters, the longer the cable, the more it matters. Maybe the cat5 had a more "right" impedance than the "computer" cable. I'll look a bit into ther cat5 specs.

How about just a balun? Probably cheaper than the high end cable you might need to buy to run RS232 a long distance.

I've run RS232 from an XP-8 to a RJ45 to BD9 adaptor into a Denon receiver over a 30 m (about 100ft) run without any trouble.

We just finished a project that had a distibuted video system in it that one of the panasonic plasmas was about 200' of wire from the XP8 at the head end and the RS232 worked fine. We had another location about 300' from the head end but ended up putting in a PCM8 so we never tested RS232 that far.

As others have mentioned, the spec just says it will work at least 50' and that is up to 115.2K baud. Most devices we are controlling are 19.2K baud and under which aids in reliability over long distances.

" One good trick would also be to balance the rs-232 communication, just put 2 transformers 1:1 on each side, and run the balanced signals in a twisted wire pair cable"

Or use a 232 to 422 convertor, since 422 is already balanced.

232 is only stable to around 75 feet depending on the baud rate. As mentioned, you will need to convert to 422

Spec is: 50' - standard cable, 250" - lo-cap cable.
My take - try. If doesn't work use RS232 to CAT5 converter and you are set. Of course it adds to the cost, but converter will bail you out.