Great write-up on UPB vs. X10

[kwilcox]

My UPB switches respond about twice as fast as my X10 switches. This is very noticable in my motion sensor controlled lights. UPB, like X10, is succeptable to collisions when multiple commands are placed on the powerline simultaneously. However, the protocol contains built in re-transmission capabilities to minimize this. Plus, unlike X10, there is a short "ack" packet built into the UPB protocol that provides necessary feedback that a command has been carried out.

There is no relationship to the size of the UPB installation and the speed of any given UPB command btw. A 200 switch application will operate at the same speed as a 5 switch application. The only thing that could affect transmissions would be large numbers of devices simultaneously placing information on the powerline. In UPB's cased that could only be if large numbers of switches were pressed simultaneously, an unlikely scenario for sure. There is no need with a UPB installation to periodically issue all device status requests as many do with their X10 installations since the automatic ACK built into the protocol insures that the controller is in sync with the actual state of the UPB devices its commands. I've noticed, btw, that issuing a status request to a UPB device returns a result almost 3 times faster then issuing one with an X10 device.

Remember too, that the UPB link paradigm insures that large numbers of devices can be controlled very quickly. This is very much unlike the X10 group command where all devices in the group must be enumerated in the command itself. UPB simply sends the link ID and all devices in the link respond with their own stored responses.

Bottom line IMO is that greatly increased transmission speed coupled with the fact that the protocol itself is optimized for the characteristics of powerline transmission results in a highly reliable, fast HA system. This must be the reason why professional installers are doing very large UPB installations. I myself am excited to begin offering UPB installations. We're printing up the marketing materials now and I should begin installing UPB sometime in Q3. This based on my own testing. The difference between UPB and X10 is night and day.

 

[rocco]

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".

Sorry, adsbar, I think I kind of mislead you with my post. I do not believe UPB is slow.

If 1/120 of a second isn't noticeable, I'm fine with it.

1/120 of a second is not noticeable (well, maybe if you're a hummingbird). Some perspective:

It is 5 times faster than a single frame of film at the movies (1/24 of a second), and you are not expected to notice each frame.

A mechanical light switch has a debounce time near 20 milliseconds (1/50 of a second). So the additional latency is half of a mechanical switch.

1/120 of a second is 80 times faster than X10 (2/3 of a second). Not that UPB is that fast, but the additional latency from the low baud rate is.

What I was trying to say in my previous post was that the latency caused by the 4800 baud-rate was not significant, but that it did allow a longer serial cable. For what it's worth, the time it takes for a round-trip UPB sequence (command plus acknowledge) is half that of a one-way X10 command.

 

[ChrisWalker]

Just to add to rocco's post:

As rocco said, the 1/120 of a second post was about additional delay caused by the latency of 4800 BPS. For the actual UPB protocol, it is approx. 240 BPS if I remember right, meaning each command going across the wire would be more like 1/8 of a second or so.

UPB seems like a nifty protocol, but like all others it does have its caveats and places where it is most useful.

Chris

 

[kwilcox]

That's pretty much correct. You get that speed from 2 bits/sinewave transition * 120 transitions per second. Transmission time is actaully a third of a second since each UPB frame is 80bits long. That's the delay you'll experience when you initiate a UPB event. By comparison, a typical X10 frame takes about .8 seconds to transmit. Hence the "UPB is about twice as fast as X10" analogy.

 

[AutomatedOutlet]

I installed about 9 UPB devices in my house this last weekend. I will continue to add devices. So far, everything is going great and I like the speed.