Re: Probe Hub Update

["Graham Howe" <graham@xxxxxxx>]

--- In ukha_d@xxxxxxx, Frank Mc Alinden <fmcalind@b...> wrote:
> Hi Steve
>=20=20=20=20=20=20=20=20=20=20=20=20=20
>             Didnt explain that too good ...What i meant was that it=20
would monitor the "Actions"of the momentry switch.. ie 0% or 100%
but=20
not % brightness....Doesnt homevision keep track of each load ???
> Frank

Like I said, this approach won't be much use with momentary switches=20
as several can connect to a single LD11. Also momentary contact acts=20
as a toggle, so if HomeVision or Comfort or a timer or anything else=20
changes the state of a light, then knowing that someone has=20
subsequently pressed the switch will be of very little use.=20
HomeVision does keep track of what it thinks the state of each module=20
is, but this (in a European environment) is based purely on the=20
commands passed through HV. It has no way of actually determining the=20
load or status of a module here.

As an example of how messy this could get, consider the following=20
scenario based upon one of my lights:

1. Following a power cut HV comes back to life and knows to set the=20
light to OFF. - Light now at 0%
2. Someone presses and releases the single momentary switch. - Light=20
now at 100%, HV thinks it is at 0%, assume a probe detected the press=20
and that HV now has the light at 100%.
3. HV dims the light as part of the bedtime macro. Light now at 25%=20
and HV has the light at 25%.
4. Some one gets up during the night, Comfort detects the movement=20
and brightens the light to 50%. Light now at 50%, HV has it at 25%=20
(unless HV has detected the x10 traffic, but I haven't actually tried=20
this).
5. Person returns to bed and dims the light to approximately 25%=20
using a momentary switch. Light now at 25%, HV receiving a button=20
press from the probe toggles the status to 0%.
6. In the morning someone presses the button to turn off the light.=20
Light now at 0%, HV receiving the button press from the probe shows=20
the light at either 25% (the last ON level) or 100%.

In the space of a routine night, HV now has the wrong status of the=20
light even with a sigle button and every action being captured=20
correctly. Once you start to mix in multiple switches and other x10=20
traffic and the potential of HV not noticing and x10 command then I=20
can't see much chance of HV knowing the real status without measuring=20
the output.

Of course one alternative approach is to have the momentary switches=20
wired back to HV or some other controller rather than directly to the=20
LD11s. That way the LD11s can be controlled via the controller and=20
the controller will always know the status. However this makes=20
subsequent removal of x10 significantly more difficult, means that=20
lights are 'at the mercy' of the controller and in the case of HV=20
would severely limit the number of zones available as it only has a=20
few ports.

Of course if any of you electronic wizards want to prove me wrong=20
then please do, I will be the first to hand over my cash for HV to=20
genuinely know what status all my LD11s really have.