Opentherm Gateway

[Rene]

OK, no problem. We tried and now we know.

Maybe we should make a matrix of thermostats and the commands they support.

[hvxl]

I did start something like that: http://www.tclcode.com/opentherm/matrix.html. But that only shows which message IDs the thermostats generate and what the boilers support, not details like this.

[Rene]

I will collect this information for the Remeha Calenta boiler and iSense thermostat.

[Rene]

Is it possible to send a self crafted OpenTherm request, for instance requesting the return water temperature? The iSense does not seem to request the return water temperature.

[hvxl]

That's what the AA command is for. For example, AA=28 will add the return water temperature message ID (28=0x1C) to the list of things the gateway will request from the boiler whenever the thermostat sends a message that the gateway already knows the boiler doesn't support.

[Rene]

But the thermostat seems to never send a message the boiler does not support, so this would mean waiting forever.

[hvxl]

Your earlier excerpt from the logs already showed some messages the thermostat sends and the boiler apparently doesn't support: ID's 20, 21, and 22. But as you indicated, those each only happen once per hour. But then there's also message ID's 9 and 100, which should happen more frequently. And judging by the document you just sent me, the iSense also sends ID's 4, 99, 109, 110, 111 and 112, which are not listed as supported by your boiler.

[Rene]

You are right, AA=28 works great. I didn't understand DataId 99 (0x63) was not supported by the boiler, because I did not see a response from the boiler but only a response from the gateway.

[hvxl]

Correct. After a reset the gateway initially passes all messages from the thermostat on to the boiler. It learns which messages the boiler does not support by keeping track of the messages that get an Unknown-DataID response. It never sends those messages to the boiler again. Instead it uses the timeslot to obtain other information from the boiler. So, if the gateway doesn't relay a particular message from the thermostat to the boiler, it means it has already learned that the boiler doesn't support it.

[hvxl]

I did start something like that: http://www.tclcode.com/opentherm/matrix.html

I have automated the analysis of the otmonitor log files. Anyone can now upload a log file to add their equipment to the matrix.

[RDNZL]

Did someone program their PIC themselves?
With the help of those simple programming schematics you can find?

Looking for one for Linux or Windows.
The ones I have found didn't work under Windows7

[fabian]

I've used a velleman programmer board velleman.eu/products/view/?country=nl&a ... ;id=350903 and windows XP.

I'm guessing the main problem with programming using more recent windows version is 'direct access' to the serial port.

[RDNZL]

Yes the lack of direct access is the problem, I can look for an old thin client at work with Windows XP on it.
The funny thing is (or not) I have a Willem-Prog PCB 3v5.6 board, it can program almost anything, has a ton of sockets, but it can't program a 16F88
home.arcor.de/sylwester-kus/index-datei ... rog_5.html

[Digit]

I bought a Microchip PICkit 2 recently; haven't tried it yet, though.

[Templar]

Hi all,

I made my own gateway thanks to Lennart. I did not place the MAX232 IC however, instead I used a JY-MCU bluetooth module. I configured the bluetooth module with a USB BUB, the settings are retained after disconnecting power.
The only disadvantage I encountered is the time delay in pairing the device and loose important Data-ID's during power-up. I had to disconnect the thermostat to restart OT communication.

Templar