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Details about the X10 PLC Protocol

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rowan.bradley:
I'm trying to fully understand the X10 Power Line Communications protocol prior to writing some software. Firstly I have been unable to find a full specification for this anywhere. Where can I find this? The main questions I have at this point are:
1. Can I address several units and then send commands to all of the addressed units? Exactly what sequence do I need to use to do this?
2. The information that I have seen tells me that successive Bright or Dim commands must be sent without any intervening quiet period. If I want to send 5 Dim commands to a device, what is the exact sequence for this?
3. What exactly should be the response to a Status Request command? What Letter Code should the device send?
4. How do I read back the value from a sensor, which may be 16 bits long? What command(s) do I send, and what does the device send back to me?

Thanks - Rowan

JeffVolp:
That information can all be found by spending some time with Google.  Most is answered in the X10 Technical Note that is available at multiple locations, including our own website:  http://jvde.us/info/X10_protocol.pdf

To handle 16 bit data you will need to use extended codes.  There is another document for that, but it is not currently available on our website.

Quick answers:

1)  Yes, on the same housecode:  A1, A2, A3, A_ON
2)  The dim commands must be concatenated with no gap between if you want to slew to a different level.
3)  A1, A_Status Request -> A_Status_ON
4)  Extended commands (you will have to read and understand the document).

Jeff

dhouston:
There's a PDF on my website that covers standard and extended codes.
https://www.laser.com/dhouston/X10 xtdcode.pdf

Brian H:
Only a very few X10 modules are two way with a power line transmitter in them. So trying a Status Request on most modules will get no reply back.

LM14A, AM14A and the RR501 modules are the ones I can think of offhand.

Some of the Insteon Modules could also have an X10 Primary Address added to them. They where two way and will also respond to a Status Request or send a status change from the local control on the wall switches. One thing that is different. They used the %Dim commands and a Status Request would have a %Dim reply in the answer back.

rowan.bradley:
Thank you for those helpful replies. I had in fact already spent quite some time searching with Google, and I had already found the document TW523 Technical Note, but it seemed to me that this was more about using X10 via the TW523 than directly. I will read it again, and see whether it gives me the information that I need.

Thanks - Rowan

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