Re: failsafe data collection, was Last Night in London?

[Stuart Grimshaw <stuart@xxxxxxx>]

You could use something like the DS1921L-F5x, this will store up to 2048
consecutive temperatures in ROM, it also comes with 4096bits of RAM, and
has
an RTC. It will even continue to record temperatures when power is
disconnected. It's applications suggested are things like recording the
temperature of something in transit.

On Sunday 24 June 2001 11:15 am, you wrote:
> sort of.  i want the houses status to be distributed around the house
in
> case of failure.  Each sensor has its own nvram chip so whenever you
> collect a temperature the local storage is updated with the info.  A
> collector thread runs at a lower priority to run this data off into
your
> historical database.  An example of why this might be useful is after
a
> system crash (house power failure).  The power is out for 20 minutes
on
> reboot each temp sensor is queried for current status.  Given all
lighting
> heating has been off the temperatures recovered might not be
appropriate
> given the current status outside.  Alternatively you might lose the
> historical database so its impossible for the system to determine the
> historical time series for each room.  In this case you can fall back
onto
> the nvram chips to give you a clue to the current status of the house.
The
> primary function of each nvram is to associate addresses to each
sensor and
> provide limited historical data about the environ in which its located
> should there be problems with the control units.
>
> k.
>
> -----Original Message-----
> From: Stuart Grimshaw [mailto:stuart@xxxxxxx]
> Sent: Sunday, June 24, 2001 11:10 AM
> To: ukha_d@xxxxxxx
> Subject: Re: [ukha_d] Last Night in London?
>
> On Sunday 24 June 2001 10:53 am, you wrote:
> > Stuart,
> >
> > device will switch it on and off.  XML on the nvram chips
detailing its
> > location can be overlayed on top of the vrml describing the
layout of the
> > house/flat. The NVRAM has to be updated by the controller because
I cant
> > afford the expense of a TINI in each sensor unit but I want to
have the
>
> So the NVRAM data would be used for other devices that don't have
access to
> the db on the main controller, rather than the main controller to use
to
> recover data from the period it was down...? Starting to make sense
now....

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