Power line comms X-10

**versatronics** · - 29th November 2007, 06:32

Hi Guys
Wow! thanks for all the info, I'm gob-smacked at the complexity of some of the applications, but agreed, if you want that level of addressability and control it's needed. I just wanted to turn the geyser on/off and one light!! so I will get inspiration from the circuits particularily the mains interfaces, and just use some simple PPL tone switching at 2 different frequencies, the didtances are pretty short and I should mangae without zero crossing detection or phase control etc and just stick to a simple go on/off to 2 devices. I'll give X10 a miss and just output a high on a pic port to turn on the PLL. But thanks a ton for the info.
Graham

**Darrel Taylor** · - 29th November 2007, 08:02

Well, he might have given up, but I'm still curious Dave.

Is there another extended command set I don't know about.
Not trying to be contrary, I just want to make the previous posts as complete as possible.

I wasn't exactly thorough in my search last time, but those were the only other X-10 commands I could find.

Are there more?

**dhouston** · - 29th November 2007, 12:16

Darrel,

There's a text file on my web page listing all X-10 commands. Originally, it was a .DOC file that was so horrendously formatted that it was nearly impossible to read so I reformatted it as the text file. Later, X-10 made it into a .PDF and I reference that URL at the top of the text file.

http://davehouston.org/xtc798.txt

Many of the commands described have not been implemented by existing hardware although X-10 Europe seems to be using more of them than X-10 USA. This is probably because CE rules required them to redesign most of the hardware sold in Europe a few years back. Here, the LM14A and AM14A use some of the extended command set as do some dimmer switches made by Leviton (who confuses things by calling their Extended Dim commands Preset Dims). You need a more sophisticated interface to receive these commands - CM11A, CM15A, and some of Smarthome's interfaces. There are European equivalents to the CM11A.

There's a subtle thing (well, not really all that subtle but it's not explicit in their documentation of the power-line protocol and these devices) about the X-10 TTL two-way interfaces (TW523, PSC05, TW7223, XM10) that most people miss. It only reports valid codes it sees on the power-line. This means it cannot report in real time, since it needs to validate a whole code or 22-bits, but must delay one whole command-worth of time (22 half cycles of the 50Hz or 60Hz). In other words, what it reports actually occurred about 1/4 second earlier. And it cannot report continuously - it reports only every third command in the case of Dims and Brights and reports only the first 22-bit chunk of the longer extended commands. And it will only report valid codes, which must begin with 1110. It acts a bit like a 22-bit shift register with the clock being the power-line frequency.

You did say you want to be thorough.

**dhouston** · - 29th November 2007, 12:23

Originally Posted by versatronics

... I will get inspiration from the circuits particularily the mains interfaces, and just use some simple PPL tone switching at 2 different frequencies, the didtances are pretty short

I think there's an even easier way that doesn't require power-line comms. You can use a current transformer or hall-effect current sensor from Allegro to sense when the geyser is on or off and use RF links to communicate.

**dalescnc** · - 29th November 2007, 12:52

Graham seems we have similar things in common ;-) just started on a project using to pic's 1 as a master other as a slave to control 6 relays to switch 12v lights on & off. Im limited to 2 wires gnd and positive. I have found the impedance of the supply voltage been a car batt. need to modulate @ app 11mhz in order to get the signal down the line. If anyone could share some light on this idea i would appreciate it no matter what

Many thanks
dale

**versatronics** · - 30th November 2007, 06:44

Hi Dale
Did you really mean 11MHz? This is very high for PLC although if achieved will give you good noise immunity. Yearsd ago i developed a PLC (power line carrier) remote control system for the coal mines, using the trailing 5kV cables the coal cutters drag begind them. It was infeasible to connect directly to these a) as it would require the intervention of an electrician and thus down-time, and b) safety/isolation issues. so I was face with a way of getting a signal into the cable, getting adequate propagation a nd of course daling with the huge noise problem from the thyristor drive syatems of the motor. There are 2 modes to propagate into a cable: bifialr - where you excite equal and opposite signals between the pair of wires - this is hardest to do but has less line attenuation; and monofilar where you exite all the wires togethher as a bundle against a earth reference. This is easiest to do with an inductive coupler of some sort and needs no connection to the wire. however to electrically 'space' the wires apart I had to go up in frequency, also to get above the noise harmonics I used 4MHz This is very much higher than the usual 120kHz type carrier. i know this doesn't help much but you might find it interesting to see that high frequencies do have a place. The modems were designed with discrete phase locked loops and use FSK at 9600b/s. -- I may still use something like this for my house!!