[OpenTRV-interest] OpenTRV board as 868MHz transceiver

[Marko Cosic]

On 10 January 2016 at 02:49, Alasdair Macdonald <
alasdairgmacdonald at gmail.com> wrote:

> What I want to do
> is use fhem to make decisions about whether to open or close my Conrad
> TRV, but what's happening is that the board that is paired with the
> valve is making all the decisions.
>

This sounds a lot like the COHEAT code variant Damon.

(PC makes decisions, sends these to an OpenTRV board using a REV2 board,
the OpenTRV board relays the decisions to the Conrad valve (ELV FHT8V) and
spits back some room sensing data)


When a non-Hub board pairs with a Conrad Valve, the valve knows that
> it is paired. I don't know if there is an ongoing, occasional dialogue
> between paired devices, but in this relationship the OpenTRV board is
> still a transmitter, and the Conrad Valve a receiver. I don't know if
> the Conrad Valve actually transmits any information, perhaps someone
> here can put me straight on this.
>

There's an ongoing one-way transmission to FHT8V valves


* Have an OpenTRV board that can send data to multiple TRVs, on an
> ad-hoc basis. I don't know enough about pairing (and I only have one
> Conrad TRV) to know if I can pair with multiple TRVs.


One OpenTRV board one FHT8V is easier


 I don't know is at all sensible (in the case of multiple
> radiators / TRVs) to change House Code (and re-sync?) whenever I want
> to control any individual radiator.
>

Normal one-way transmissions to the FHT8V valves is a signal every 2
minutes.

Re-sync is 2 minutes of almost continuous broadcasting. You wouldn't want
to do this every time you change a valve position and it would not make the
FT8B receive it any faster.



> * Set a mode and target temperature such that the board will send a
> command to open or close its paired TRV. (And I'm not sure what
> strategy to use here, given that essentially I want to "trick" the
> OpenTRV board into sending its own command to the TRV).
>

There's a lot of art in what OpenTRV have coded in TRV control.
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