Re: EIB Instabus

["David Buckley" <db@xxxxxxxxxxx>]

--- In ukha_d@xxxxxxx, "Ian Lowe" <ian@w...> wrote:
> -----Original Message-----
> From: David Buckley [mailto:db@e...]
> >But I'm sceptical as to whether IP will ever be a core control
> >protocol,
>
> ... Moore's law comes racing to the rescue, and the simple
> passage of time does the rest.

Thats true as far as the silicon is concerned, a PIC (or atmel or
whatever) that can _comfortably_ run a _real_ IP stack with all the
bells and whistles, and costing next to nothing can only be a short
while off.

But - ethernet requires magnetics and filters, and these components
are not subject to Moore's law, only volume production, and they are
already pretty cheap, but still more expensive than a micro.

As to EIB - dont underestimate how big EIB is - EIBA claim 10m
devices shipped mid 2000.  And the big thing - EIB runs over several
media layers: twisted pair, powerline, RF, IR, and TCP/IP.  So even
if TCP/IP does become ubiquitous, EIB is there.

But the question will be - do people want a system like CBus which
is proprietry, but is fit and forget, and just works, or a system
that is dependent on the home LAN for operation?  Thats where I
think ubiquitous LAN technology will fail.  Its just not as reliable
as a dedicated system.  And if you are an installer, that matters,
as you dont want the service calls!  Not to mention having to star
wire Cat5 to a hub somewhere (or many cascaded hubs?  Hubs under the
floor anyone??), more work.

And I'm not sure that the end result is any better than a hardwired
EIB or CBus with an interface to the public world.

I read an article recently about the Sydney Olympic stadium, and
that they have a canned show utilising the big flame thing.  The
show elements are all run off show control technology (MSC, DMX512
etc), but they needed to interface with the CBus controlled fixed
stadium installation.  The solution - contact closures.  Low tech,
but works, all day, every day.

I'm also of the opinion that the really reliable control systems
achieve much of their reliability by being in control of their MAC
layer.  For example, CBus has the concept of a "network
variable",
which CBus aware folks will know as a group.  CBus network variables
(a byte value, 0-255) have the property that they are consistant
across a network, as the CBus system _guarantees_ that either all
instances of the network variable are updated, or none are.  You can
only do this stuff if you have control at the wire level; under most
layered protocols (eg IP) you loose control partway down the OSI
stack to some other provided facility, and thus you cant see exactly
whats happening on the wire.


> But hey, this is all just shooting the breeze... (it's
> fun though ;) )

Sure beats the hell out of life :-)

Bottom line is - almost all homes are still wired using conventional
technology, and that will continue tobe the case until the price of
an alternative approach drops below what we do today.  'Till then,
this stuff will always be a niche technology.

Tripling the price of energy would help, as then people would
want "better" control of their expenditures!!!