OTGW used to simulate a boiler device

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OTGW used to simulate a boiler device

Postby warp » Sat Sep 14, 2019 11:45 am

Hi,

I recently bought a thermostat (toon, for testing purpose) that can communicate with a boiler using opentherm protocol.
Unfortunately my boiler is not compatible with opentherm.

I have a RPi that is connected to the boiler using optolink (see https://github.com/openv/openv/wiki/Die ... nittstelle for information ). Almost all commands work.
I can read values, change setpoints, change heating mode...

I was wondering if I could use this OTGW as an intermediate appliance between the thermostat, and the RPi.
So that there would be nothing to change on the thermostat.
Obviously I would need to code the communication between the OTGW and the RPi, but considering the hardware fits to my use case.
Thanks.
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Re: OTGW used to simulate a boiler device

Postby hvxl » Mon Sep 16, 2019 10:26 pm

If you use the interface firmware, you could write some code that will receive an Opentherm message from the thermostat, translate that to the appropriate optolink value, and then generate a response back to the thermostat.

Officially, a slave device should respond within 400 ms. I don't know if that is enough time to actually obtain the requested information over optolink (at 4800 baud) on the spot, or if you have to prefetch information so you can return it immediately without having to send a query over optolink at that moment. You can also decide to relax the requirements and aim for the 800 ms interval, within which the master device must receive an answer.
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Re: OTGW used to simulate a boiler device

Postby warp » Mon Sep 16, 2019 11:27 pm

So from a physical point of view it can work (with the interface firmware).
I did not think about the protocol timing.

There’s no need to have real-time data. A delay of some seconds is totally acceptable.
Currently everything is cached in Domoticz, so data will be directly available.

...anyway, I think that’s enough to give it a try...
I’ll post again in some ...weeks ?... with my setup description and test results.
Thanks
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Re: OTGW used to simulate a boiler device

Postby marcelr » Wed Apr 29, 2020 9:14 pm

Hi warp,

It's been quite a while since you last posted here. Did you get any further in your queries?
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Re: OTGW used to simulate a boiler device

Postby mariobkk » Sun Jan 10, 2021 7:18 am

Hi,

Looking at the same scenario with a 9kW E-CV. The E-CV is original just ON/OFF but we have rebuild using SSR to switch the 3 heating elements to switch 7 powerlevels. We're using a WP8028ADAM as relay and OpenHAB for reading the Nodo OpenTerm gateway info and calculate the next relay position based on modulation.

Our setup is currently thermostat -> heatpump -> Gas CV (To be replaced with our E-CV solution)

If anybody has more info in simulating a CV using the OpenTerm gateway we would be most interested.

Mario
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Re: OTGW used to simulate a boiler device

Postby mariobkk » Mon Jan 11, 2021 1:30 pm

Update fom my end.

The OTGW from Nodo Shop works great. Tested using NodeRED to receive the data and answer to message with reply using the serial command and that works as advertised. However I need to send a reply and there is as far as I no serial command to return "raw" data to the Thermostat to simulate a boiler so the OTGW will become the monitor between the Thermostat and the heat pump.

To be continued, find a OpenTerm gateway that will be able to send "raw" data that I can program as I unfortunately have no assembly knowledge.

Any recommendation for a gateway that would support sending free data back to the Thermostat is appreciated.
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Re: OTGW used to simulate a boiler device

Postby hvxl » Tue Jan 12, 2021 11:16 am

mariobkk wrote:Any recommendation for a gateway that would support sending free data back to the Thermostat is appreciated.

The OTGW can, if you load the interface firmware.
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Re: OTGW used to simulate a boiler device

Postby BarthoD » Wed Jun 02, 2021 9:20 am

Did you succeed? Is it solved?
I have the same kind of problem with a SUN-Boiler that I need to run stand-alone. This sun-boiler is working as a gateway expects an after-boiler (CV) as end-point.
All I need/want is to use the OTGW in the regular way, but as output of the OTGW (where normally the thermostat resides) I like to have the ability to just simulate a boiler (axactly as the request in this topic).

See also https://www.domoticaforum.eu/viewtopic. ... it=ferroli for more details.
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