Re: A mentor / Advisor ?

[nobody@xxxxxxxxxxxx (Dave Houston)]

"Dean Roddey" <droddey@xxxxxxxxxxxxxxxx> wrote:

>They have a .Net based class framework that is a much simplified interface
>to the Z-Wave hardware. It is 'built over the SDK", but you have to realize
>that all the SDK is (for non-hardware building folks like us) is just the
>definition of the messages that you send over the serial/USB port. So it's
>not that they are layering their software over some SDK software, since
>there is no SDK software really for folks just wanting to talk to the Z-Wave
>controller from a PC. They are just using the information documented in the
>SDK of the message formats to create an easier to use framework that hides a
>lot of the details.
>
>Of course, if you don't use .Net, then it's not terribly useful to you. I
>think that they should have used a lower level language so that it would
>have wider applicability.

If it's based on the pseudo-USB of the FTDI chip then it's useless to
anything that doesn't run under Windows, Linux or OS/X (e.g. embedded
µControllers like ELK) as an FTDI driver is required to interface with the
FTDI chip. That's rather silly given that it is an RS-232 interface with the
FTDI chip added on - the data has to be translated on both ends and it's
slower overall than it would be if they just used RS232.

>> Finally, can the devices from various manufacturers send instant level
>> feedback and can the various controllers import the routing tables created
>> by the latest controllers?
>>
>I'm not completely sure if the first generation modules can do this or not.
>They using a trick that gets around the Lutron patent. I cannot imagine how
>someone got awarded a patent for sending the status of a device over RF, and
>I find it ludicrous, but they have it, and so no one can send direct status
>feedback from a lighting module via RF without running into Lutron's patent.
>Z-Wave uses some trick with links. I guess non-light switch devices can send
>status directly without patent problems, but I don't know if any are or not.

The inability of secondary controllers to register changes occasioned by the
master controllers (changes in dim level or changes to routing tables) was a
frequent complaint from early adopters. While there were 3-4 companies
supplying Z-Wave hardware, the only differences in their first generation
hardware was the color of the plastic enclosures - all were merely using the
Zensys reference designs. Perhaps that's changed but I doubt it.

There are FCC requirements for Part 15 devices (I think the 904MHz used by
Zensys falls under Part 15) that require reduced power (about 50%) for any
non-human operated device that sends _data_ via RF. Basically, anything
beyond the simple "all's clear" status reports of wireless alarm sensors
must use lower output power. This is why there are frequent complaints about
the poor range of wireless weather sensors. (A 50% cut in power causes a
much greater than 50% range reduction.) I would expect this might be a
bigger factor than any patent although I've been through the patent process
a few times and the creative writing skills of the patent attorney are
frequently more important than the technical merits of a device.

I hadn't heard of the Lutron patent before. I wonder whether it is a factor
in the lengthy delays for the ZigBee based systems from Eaton and Hawking.

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