Man at B&Q wrote:
On Apr 27, 9:34 am, John Williamson
wrote:
Man at B&Q wrote:
On Apr 22, 11:14 am, Andy Dingley wrote:
On Apr 22, 4:00 am, Bob Minchin
wrote:
Andy Dingley wrote:
On Apr 20, 5:10 pm, Bob Minchin
wrote:
I have found the answer herehttp://universalmeterservices.co.uk/store/images/5193.doc
Meter Memory
All the meters data is recorded in a Ferroelectric Random Access
Memory (FRAM) under the control of the microprocessor. All the kWh
registers are stored in theFRAMand are updated every 1/100 th of a
kWh. TheFRAMis guaranteed for a minimum of 10,000,000,000 write
cycles
WTF? Core memory?! 8-)
Yes I found that difficult to credit but I suppose it maybe used to meet
a possible regulatory requirement for N years retention with no power
connected??
Not quite core, but not completely unrelated and quite interestinghttp://en.wikipedia.org/wiki/Ferroelectric_RAM
It's been around for quite a while. FLASH and EEPROM are mostly
useless for this type of application. Given it's an electric meter
they could just use low power SRAM with a super cap backup supply.
MBQ
Too easily corrupted.

Easily designed around.

To use one example meter I know of, in what was an empty shop for three
years, how would your idea cope with a couple of years of disconnection?

Fe RAM has indefinite data retention after removal
of power, better than 10^^15 write cycles, and a glitch during writing
won't corrupt the rest of the data (According to the makers...)

You would struggle to "corrupt the rest of the data" with any
technology.

I must remember to tell the makers of my cameras that. They tell me
under no circumstances must I take the batteries out while it's writing
to the card, as that may render the card useless.

--
Tciao for Now!

John.