Care to share your circuit and code?
OpenTherm VR33 and Vaillant ecoTEC plus 428
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I'm just using the circuit shown here https://ihormelnyk.com/Content/Pages...chematic_o.png and also the same here https://registry.platformio.org/libr...raus/Opentherm
The code is using the J Praus opentherm library and I've based my code on his example. The only real change was to add a timeout into his 'conversation' handler so that it would reliably detect if the boiler didn't respond.
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I've been trying this out but I'm having some problems.
Whilst the loop is applied to the VR33 OT connections then the boiler works fine in response to the 240V demand signal as it always did.
When I connect the OT up to my Arduino and start sending commands I can see the boiler is receiving the feed temperature control correctly but it never fires up. It seems to be ignoring the demand signal.
I had initially not been sending the OT slave config message so I thought perhaps that was an issue so included that with the ch_enable bit set to 1. Still no change though.
As soon as I put the loop back on then it fires up correctly.
Any thoughts what might be wrong?
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I've confirmed it's working correctly now. Sending the STATUS message with ch_enable set to 1 is what it needed. The demand control into terminal 4 is working fine alongside the OpenTherm temperature control. Sorry for the false alarm on this.
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