Electrisave protocol

["iaingoodhew" <I.C.B.Goodhew@xxxxxxxxx>]

Great news for anybody who has an electrisave usage monitor. I've=20
managed to reverse engineer most of the electrisave protocol and=20
read the electricity usage into the PC. It's really early days at=20
the moment but if there is significant interest a beta product may=20
be on the cards. Details below:

The electrisave units can monitor upto 3 elctrical circuits, sensing=20
the electricity usage by the amount of current flowing in a=20
conductor using a sensor clamped around the wire. The unit sends the=20
data to a remote display unit via radio on 433MHz, which can display=20
the data in a variety of formats (current, Kilowatts, Cost etc).=20

The prototype PC adapter consists of a 433MHz AM receiver and a PIC=20
microcontroller. The PIC constantly monitors the 433MHz receiver,=20
and decodes any electrisave packets into a binary stream. The data=20
is then sent as decimal bytes via serial to the PC, where the data=20
is displayed in hyperterminal, or similar.

Data is in the following electricsave format:

Counter, UNIT ID,  Current1, Current2, Current3, Unknown, Unknown

Example below
6,221, 40,  0,  0,42,22
0,221, 39,  0,  0,35,2
9,221, 37,  0,  0,42,198

My UNITID was 221 in this example, but this changes if you reset the=20
transmitter.

The current is in tenths of an amp, so you can see I was drawing=20
between 3.7 and 4.0A. (I only have one sensor). This number can=20
easily be converted to kilowatts by multiplying by the voltage 220V.=20
The unknown bytes on the end are probably battery status, and=20
checksum.

The counter on the front is used to aid power saving in the battery=20
powered display. The transmitter always sends out the electricity=20
usage on the `0' of the counter, and intermediate values are only=20
sent if the value has changed. The receiver can be set to power up=20
and receive data every sample, or only on the `0' value. Counter=20
values go from 0 =96 9.

So to my question ....Is anyone interested in a PC adapter for the=20
electrisave, if one is developed? I am looking to convert the unit=20
to be a usb powered device, but would probably look for someone else=20
to develop the PC datalogging. Any Beta units would have to be=20
purchased, as I cannot afford to finance this all myself. I am=20
looking for partners in this project to share development and=20
benifit the wider HA community. If anyone is interested contact me=20
on or off list.

Details of the electrisave can be found here.

http://www.electrisave.co.uk/

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