Extending A TW523 Data Cable


Senior Member
Does anybody know the maximum distance you can extend a data cable on a TW523 X-10 interface? I want to replace my TW523 with the new XTB-II which transmits on both legs of the AC service at once. To do this I need to put the XTB-II next to the breaker panel which is about 100 feet from my Stargate. If I use CAT5 can I get away with a data cable run that long?



You might want to email Jeff Volp and see what he has to say about the maximum distance you can extend the TW523 cable.

He is obviously pretty knowledgeable about the TW523 operating characteristics and limitations.

Just a thought.



Senior Member
I think I mentioned it once on the Stargate mailing list and Jeff didn't know. (And neither did anyone else)


Active Member
The TW523 has an opto-coupler interface that is usually operated in current mode. Also, there are no signals that need to be fast. Together, this means that the TW523 is "capable" of running on very long cables, maybe a few thousand feet.

But the detrmining factor will be the other end. The TW523 interface can run on signals from 3 volts to 20 volts. Most devices interface to it with either 5 volts or 12 volts. 12 volts would have high noise-immunity, especially if operated in current mode. The cable should not have much effect on the signal.

Do you know what the TW523 interface on the Stargate looks like? If you have a schematic, I could evaluate it, but I believe that you shouldn't have a problem with 100 feet of Cat5.

BTW: I am assuming the XTB-II is using the same interface circuit as the TW523, or if it is not the same, I assume it is better.


A TW523 digital interface cable can be extended as long as needed to reach your electrical distribution panel. The 1mS pulses sent over that cable do not have critical timing. I ran here with 50 feet, but there is no reason it wouldn't work at 100 feet or more. The only thing to consider with long runs is that there are 3 signal leads and one ground. So you don't want to use 2 twisted pair because of possible unwanted coupling. Three twisted pair running a ground with each signal lead would be ideal for very long runs.

The XTB-II digital interface is optically isolated, and virtually identical to the TW523.