Great write-up on UPB vs. X10

So what software supports the preset levels and variable fade rates? Does the Elk M1 support these fancy features or just basic on/off stuff?
preset levels and fade rates are supported without any additional hardware/software - it's all how you configure the switches. You can configure single clicks and double clicks up and down - can control the levels and the rates for each. Also, you can configure the switch to remember it's last light level.

My HVPro (Homevision Pro) will allow you to control/change these as well based on activities and actions.
can the Elk set different direct dim levels, without having to ramp up or down to them? Can the Elk do different face rates at different times?
Actually, the switches can. You simply program different levels and fade rates into any of the links that the switch stores locally. You can go immediately to any level using the "Snap" feature which essentially is a fade rate of zero. Links are actually unique UPB ids that are transmitted on the line. All switches have on-board NV-RAM that stores what, if anything, they are to do when they see this code transmitted. When a link is programmed, all devices associated with the link id are told what to do. When a link id activate command gets transmitted, all devices do their programmed behavior which includes ilumination level, led color change, and ramp rate. Ramp rate can be overridden however by transmitting the link activation code with a Goto component. This allows you to dynamically tune scene sequences and would most likely be implemented as an Elk feature. When a link id de-activate gets transmitted, all devices associated with the id turn off (although this default behavior can be modified as well). All switches can be programmed to transmit different link ids for single and double taps. UPB controllers can be programmed for many more links. All the Elk has to do is transmit links to cause any type of behavior to occur. I'm not sure if the Elk can program links, but this is essentially what UPStart is for. My HCA software actually turns off control of the PIM then runs UPStart when I want to do link programming. When UPStart completes, HCA reads in the newly exported network and modifies its database accordingly. Since UPStart was written by the same company that makes HCA, you don't hardly even notice that you're in a different program.
The interface device (PIM) runs at 4800 baud???? What's up with that kind of cave-speed on something that's supposed to be the latest and greatest powerline protocol?
Links, btw, are one of two classes of UPB commands. 250 unique Link IDs are available on any UPB network. The other class of UPB commands are the direct commands which directly tell a device to goto a specific level at a specific ramp rate. A UPB direct command OFF with no device id will command every device in the network to turn off.
Dean Roddey said:
The interface device (PIM) runs at 4800 baud???? What's up with that kind of cave-speed on something that's supposed to be the latest and greatest powerline protocol?
Count up the bits in the UPB command sequence and you'll see that UPB can place any command onto the powerline in about .25 - .50 seconds. 4800 baud is based on a 60hz sine wave at esentially 4 unique values (2 bits) per zero crossing. UPB does this by placing specifically timed pulses in one of two parts of the sine wave at about the 50V level allowing it to form 01,00,10 and 11 twice per full AC cycle. That times 60 gives you the advertised rate. UPB response time is about 50% faster than X10 btw and the 50Volt signal level gives it its resiliancy to signal attenuation.
I understand the powerline technology issues. But that's pretty dang slow for the computer to network interface comm. That's going to be a very small straw to try to suck much two way feedback through.
Well, when the status reply is only a few bytes it really doesn't take that long. Remember too that status is implied in the ACK and means "I accomplished the command successfully".
Dean Roddey said:
That's going to be a very small straw to try to suck much two way feedback through.
When I first read the spec, I worried about this as well. As it turns out, 4800 baud is the slowest baud-rate that allows the serial stream to keep up with worst-case traffic on the power-line. So, although the serial-port bandwidth utilization may approach 100% at 4800 baud, it should not need to exceed 100%.

But the bottom line:
Picking the slowest allowable baud-rate allows for the longest possible cable. But it does add almost a half cycle of latency (1/120 of a second) to each command.
That's a little concerning. I am planning to build a 5000+ sqft home, and this is the first I've heard about UPB switches being "slow". Can anyone with some hands-on experience tell me if there is any noticable latentcy in UPB commands? Does this only apply to scene lighting, or is it noticable with the actual taps on the switches themselves? This could be a huge WAF issue.

If you are seeing noticable delays, what are my options? Can anyone compare UPB with Insteon as far as command latentcy goes? I'm looking for your actual experiences, not the numbers. If 1/120 of a second isn't noticable, I'm fine with it.
adsbar - I am definitely not the expert here and others will jump in but based on everything I understand you will most likely hit the limit on supported devices before you notice any real latency. According to Martin most pros are switching to UPB and since the pros usually do large installs, it must work well. Well, at least you would think. I don't think anyone here has a really large UPB install yet. I think there are many other things that will lower WAF b4 this.

Hey Martin - any of the pros you know that you mentioned have any real large installs they gave you feedback on?
I can't answer about a large install, my house has only about a dozen switches/recepticles, etc. However, I can answer about the delay...

Yes, there is a small delay. It is NOT instantaneous. I counted the delay for you - it is "one thou-" (if you were to count "one thousand one, one thousand two", etc). When you single tap, the delay is just long enough that if it's the first time you clicked it, you would notice the delay and just have time to think "I wonder if I didn't click it". After you've clicked the switches a few times, you get used to the very short delay and don't even notice it anymore.

Hasn't impacted my wife's opinion of these switches at all. She really likes them... likes the LED above the switch, likes the doubletaps (we set nightlight level in bottom doubletap, and full in top doubletap), and the fact that they always work (when my automation controller tells them to do something).

we usually ramp our lights (over .8 seconds), except stairs where they are instant. The only time you notice the delay is on the instant switches. With the ramping switches, you don't even notice the delay.

Hope it helps... I've been very happy with UPB.