Heatmiser protocol

["Martin McCreesh" <martin@xxxxxxxxxxxx>]

Installed 13 heatmiser stats controlling each individual radiator in a
new build and while it works well there are some major limitations with
global heating settings.

I'd like to be able to set all stats down a few degrees or to frost mode
when going out for the day to come back on at say 5 in the evening. Even
with their MC keypad to do this requires reprogramming each stat or
reprogramming one and copying the settings to all others. I'd also like to
be able to advance all stats to their next setting when we decide to go to
bed early.

I dont want to use PCLink as SWMBO wants a simple push button or timer
clock interface so my idea is to use a RS485 to RS232 convertor and write a
small routine for the atmel micro to send out predefined commands to the
stats when certain buttons are pressed.

I know there has been some work done on this but not sure if it is public
domain. If not I would be keen to find out what baud rate the heatmiser
RS485 operates at and if anybody has manged to use an off the shelf RS485
to RS232 convertor with Heatmiser where did they source.  Happy to share
results etc if I get time to figure all this out.

For those considering Heatmiser there is another major limitation of their
existing stats and that is the time cannot be configured via the bus so
time has to be set manually on each stat - a real pain... They are bringing
out a new stat to address this but the old ones cannot be upgraded. Also
they no longer ship the Master controller (no surprised as its not great)
they have a new touchscreen interface which is probably worth the money but
my budget is blown!!




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