Nefit / Buderus data/control via Arduino / ESP8266 to Domoticz (directly without OpenTherm module or Easy)

[remknul]

Do you see a message 0x91?
According to the array in my sketch this should contain the room temperature, at least for the Moduline 200.

You can quickly test if CD is the actual room temperature by pointing a hair dryer at the thermostat.

Hair dryer did the trick

both values are indeed the room temperature.
Looks like the last value is the actual temperature. And the first value seems to be a delayed version of the current measured temperature.

Is this common bahaviour to send a kind of delayed temperature?

Could perhaps also be an averaged temperature value. But looking at the data I guess it is just delayed.



To be continued...

[bbqkees]

When you are ready maybe you can send all the datagram info you found of your thermostat to the EMS wiki (or publish something on Github).

[danidata]

both values are indeed the room temperature.
Looks like the last value is the actual temperature. And the first value seems to be a delayed version of the current measured temperature.

Is this common bahaviour to send a kind of delayed temperature?

Could perhaps also be an averaged temperature value. But looking at the data I guess it is just delayed.

To be continued...

Hi remknul,

In the Buderus RC35 instructions is commented the existence of a delayed outside temperature, which is calculated depending on the building type (pages 23-24).
I do not use it, but in message Type A3 of RC35 is commented the existence of Temperature 1 and Temperature2, which is 1 delayed. Maybe the Moduline 200 has a similar functionality.

[remknul]

both values are indeed the room temperature.
Looks like the last value is the actual temperature. And the first value seems to be a delayed version of the current measured temperature.

Is this common bahaviour to send a kind of delayed temperature?

Could perhaps also be an averaged temperature value. But looking at the data I guess it is just delayed.

To be continued...

Hi remknul,

In the Buderus RC35 instructions is commented the existence of a delayed outside temperature, which is calculated depending on the building type (pages 23-24).
I do not use it, but in message Type A3 of RC35 is commented the existence of Temperature 1 and Temperature2, which is 1 delayed. Maybe the Moduline 200 has a similar functionality.

Read the RC35 instructions. Indeed there is spoken about a delayed outside temperature. But that actually is a simulation of the building characteristics which acts as a certain low-pass filter which indeed delays but also reduces temperature peaks. This mechanism is however taking place over hours and cannot be compared with the slow delay I have seen on the 2 temperature values of the room temperature.

The Type A3 diagram you refer to indeed talks about 2 temperature values of which 1 is a delayed version. Unfortunately is does not talk about the purpose of this. Perhaps it is used by other devices on the bus which want to know if room temperature is increasing or decreasing and how fast. A second query is then not needed. But this does give an answer on my question if this could be common behaviour: yes

Thanks for the info.

[danidata]

Oups yeah sorry, you are right. There are four different temperatures in the A3 packet:

• The attenuated temperature (gedämpfte Außentemperatur) which considers the building characteristics

• Current room temperature.

• The temperature 1, current external temperature.

• The temperature 2, temperature 1 delayed.

[Headwesty]

Having done something really stupid (blown up the EMS bus on my Worcester 32Cdi Compact due to bad wiring) I was digging around for details of the EMS bus. I found the EMS bus interface schematic which all makes sense (apart from lacking a pull-up - I guess the boiler provides that?).

Anyway I am trying to fix the bus and would like to know what a working EMS bus looks like. As far as I can tell:

• It is TTL levels (5V).
• It is independent of polarity (hence the bridge rectifier in the circuit)
• It sits at 5V and is pulled down to 0V when transmitting
• You can take power from the bus (while it is at 5V...)

If this is all true I'll replace the fried choke on the input (a TDK ZJY51R5-2P-0 which I will replace with this since the original is obsolete) and look to see if I get 5V coming out of the EMS port (and hopefully not blow up my nice new Bosch EasyControl in the process).

Any help confirming or denying my guesses would be marvellous!

[bbqkees]

The bus is 16V. The schematics here are for a bus slave. The bus master (the boiler) has different schematic.
Likely the EMS bus master has a fuse as well.

[bbqkees]

Just to let you know there is now also MQTT code for the ESP8266: https://github.com/proddy/EMS-ESP-Boiler

[Pat0500]

Hello Kees,

i also made the pcb and added octocouplers between the arduino and the EMS pcb just like remknul.

but i am struggeling with the arduino codes and the bus-ID from the boiler and the thermostat
i have an moduline 400 (RC35) and i figured out that the boiler its ID is 0x08 and that my termostat is 0x10
i get HEX data over the serial dump but other arduino codes like simpleregisterrequest and minimalexample i cant get value's.
could u send any example that i can sent to the boiler in the simpleregisterrequest program so that the boiler or thermostat wil reply to me?

kind regards Patrick

[bbqkees]

If you get data from the serial dump sketch, but not from the others it is likely that the write to the bus fails.
The bus dump sketch does not write to the bus, but most other examples do.
So perhaps your circuit is not working correctly.

the simpleregisterrequest sketch has to work with the default 0x19 example, if not it's your circuit.

[Pat0500]

Hello Kees,

i had an look at my PCB and indeed there was an fault but it was in my RX now it works perfectly!!!!
but i had one more question in the program receiveExample1 you have some message's regarding the RC20 thermostat but do you already looked into the messages for the RC35?
i also will look into the messages and try to change them.

this are the messages.
// 0x91 and 0xA8 are specific to the RC20 and are setting regarding the thermostat.
// If you have f.i. a RC35 you need to set other messages here.
0x10,0x91,0x01,0x04, //#13 12 setpoint room temperature x 2
0x10,0x91,0x02,0x05, //#14 13 room temperature x 10
0x10,0xA8,0x17,0x81, //#15 14 setting 0=low, 1=manual, 2=clock
0x10,0xA8,0x1C,0x84, //#16 15 overruled clock setting x 2 ( 0 = not overruled)
0x10,0xA8,0x1D,0x84 //#17 16 manual setpoint temperature x 2

kind regards Patrick Postma

[bbqkees]

The RC35 works a bit different than the RC20. I did not have time to really dive into the RC35.
You can check the Github of Danidata that uses the RC35. There you can extract which parameters are written and copy those in the receiveExample1 sketch

[danidata]

Hi Patrick,

As Kees says, I have done some work regarding RC35 controller. I have uploaded some code in this Github project. More documentation can also be found in this blog.

Regards,

Daniel

[bbqkees]

If you have a Moduline 400 instead of the RC35 some datagrams will be different.

[danidata]

If you have a Moduline 400 instead of the RC35 some datagrams will be different.

It is just a tough but, if the hardware of both thermostats are equal, can this datagram difference come from the firmware version installed?

I have found that some commands that should work in my module according to other developers (for instance, updating the RCDatetime), fails on my RC35. What version is installed in your module?

[bbqkees]

A while ago I added some more information on my Github page about the thermostats.
https://github.com/bbqkees/Nefit-Buderu ... hermostats.

I purchased a second hand ModuLine 400 for testing, but I did not really had the time for some reverse engineering.
The firmware is ML400 V3.03 according to the label on the chip.

[danidata]

I don't know if this 3.03 is the UBA version, in my case I got this values:

[bbqkees]

Looks like your RC35 has 'a' version 1.06.

In itself these numbers are meaningless.
Maybe you have a firmware build V1.06 but of type RC35 and I have V3.03 but of type ML400, so no way to compare those two.

Your built-in RC35 may also have a different firmware type than a wall mount RC35.
How do you control the temperature? Is there an additional thermostat somewhere?

[Pat0500]

Hello Kees,

i encountered a problem with implementing the data in domoticz i have an arduino with an wiznet ethernet shield and using ur code and changed the ip adresses.
im running domoticz on a pi3 with an lan ethernet connection but i have problems with adding my hardware into domoticz.
could you explain how i need to add the arduino in domoticz?

kind regards Patrick,

[bbqkees]

Check the read me on the Arduino-Code directory.

You need to add virtual sensors and switches.
Pretty easy.