Re: Understanding X10 Dims???

[Charles Sullivan <cwsulliv@xxxxxxxxxxxx>]

Robert,
Thanks for your response.  Yes, Dave's post is clear, but it
doesn't answer my questions.

I can direct the CM11A to send the same dims multiple times
(with a few seconds delay in between) but the dims reported by
another CM11A (looking at the actual byte reported, not converting
to a percentage) vary by 1/210, occasionally 2/210. Why the
variation?  And what exactly is being sent over the PL which
accounts for the "retro" effect of the higher (by 1 or 2) dim
value, which is most noticeable with the LM14A but also observable
with a standard X10 lamp module.

I was hoping that someone who had monitored the power line with
something other than a CM11A, or who had knowledge of the
hardware/firmware with regard to dims, could provide some insight
into what's happening.

Regards,
Charles Sullivan

On Mon, 08 Aug 2005 14:49:03 -0400, Robert Green wrote:

> I am going to take the liberty of repeating a Dave Houston post from a while
> back to hopefully free a little more time for him to design the "killer"
> powerline analyzer.  :-)
>
> ----------------------------------------------------------------------------
> ----
>
> Re: CM11A Protocol Question -- Posted by Dave Houston on 09-06-04 06:03
>
> It's been several years since I worked on this so the details are a bit hazy
> and it's early AM (I'm only on my first dose of caffiene) so you might want
> to look at my VB source code (cm11a.zip) for the CM11A at...
>
> http://www.mbx-usa.com/files.htm
>
> You cannot dim TO a specific value (unless you track the level of each
> address). You can only dim BY a specific increment.
>
> Standard dim & bright use approximately 6% steps (i.e. 16 steps between min
> & max). The CM11A documentation says there are 210 discrete levels. (It's
> hard to discern more than about 150.) As best I recall, I used a little
> trial and error to decide on the increments to use with the CM11A as the
> CM11A converts them to standard steps. If you send an increment less than
> 3-4% to the CM11A, you'll get a microstep (also demonstrated in the VB
> source) of about 0.6% (i.e. 1/210).
>
> You really need to study the PLC documentation to understand what's actually
> sent to the powerline for Dim/Bright - noting the fact that there's no gap
> between multiple commands. Phil Kingery's articles (see the Home Toys
> archives) also help but I never fully understood them (if I FULLY understand
> them now) until Dan Lanciani explained them using the following simple
> notation.
>
> DIM = 1 PLC dim command (Bright works the same)
>
> Sending a single DIM results in a microstep. Sending n contiguous DIMs
> results in n-1 standard 6% steps. Below, I use _ to represent no GAP between
> PLC commands.
>
> DIM_DIM = 6%
> DIM_DIM_DIM = 12%
> DIM_DIM_DIM_DIM = 18%
> ...
> 17 gapless DIMs = 100%
>
> But, using a space to indicate more than 3 idle cycles...
>
> DIM DIM = two microdims
>
> This is further complicated by the fact that a GAP is defined as 3 or more
> idle cycles (6 or more idle half cycles) so a smaller gap between DIMs is
> still seen as a contiguous stream.
>
> Another complication (for grasping the details) is that the CM11A only
> reports the cumulative result for Dim/Bright - it doesn't report the number
> of PLC commands. Those with the latest firmware wait for the end of the
> stream (or until it's seen 100% worth) to report. You really need something
> that gives you each bit at the PLC level to understand.
>
> Clear? ;)
>
>
> "Charles Sullivan" <cwsulliv@xxxxxxxxxxxx> wrote in message
> news:pan.2005.08.08.15.46.56.590079@xxxxxxxxxxxxxxx
>> Using a CM11A to monitor dims (brights) on the power line, I notice
>> that most X10 transmitters, e.g., CM11A, Mini/Maxi-controllers,
>> RR501, send dims (brights) according to the formula:
>>   dims = 11*N + X
>> where N >= 0 and X varies randomly - usually 2 or 3, sometimes 4.
>> The CM11A reports a maximum of 210 dims.
>>
>> The variation in X does not appear to be an imprecision in the
>> monitoring interface circuitry - two CM11As on line simultaneously
>> always report identical received values.
>>
>> A strange thing about X is that a value of 3 or 4 produces _less_
>> actual dimming than 2.  The effect is difficult to see with a
>> standard X10 lamp module (and digital RMS multimeter) because of
>> short term fluctuations in line voltage, but is very dramatic
>> with X10's LM14A 2-way lamp module.  With the LM14A, a plot of
>> either extended level (0-63) or output voltage versus received
>> dims (2-210 dims from the fully ON state) looks like a sawtooth
>> curve with "tooth height" of as many as 6 extended levels or
>> almost 10 percent.  (There's a similar sawtooth curve from the
>> fully OFF state when brights are received.)
>>
>> Can any of the X10 hardware/firmware gurus on this newsgroup
>> explain the reason for the variability of X in the transmitted
>> dims and the strange retro effect of X = 3,4 versus X = 2 on X10
>> modules?  Thanks for your help.
>>
>> Regards,
>> Charles Sullivan
>>
>>
>>
>>
>>
>>
>>