Monitor solar heating with ebusd

I have Wolf flat-plate collector on my roof to heat water in the bottom of the warm water tank. There is simple monitoring (Wolf BM Solar) which shows whether heating is on and temperatures on the collector and in the tank. I wanted to see this data in my Home Assistant.

Wolf does not support OpenTherm but eBUS. After short searching on internet, I've found eBUS adapter which can monitor/control eBUS devices (mainly boilers). Delivery took about 2 months but finally I have it now.

First steps with the adapter are well described. Yet I had some issues:

• flashing and accessing web interface (easi) was fine
• I've struggled with easi authentication - after entering credentials, accessing it from the same browser still worked. Only accessing it from another browser timed out and I don't see a way how to enter credentials (passing them in the url does not work). I will dig deeper into it later. UPDATE: it's fixed by 2023-09-03 firmware.
• I run ebusd on my Turris router in docker. For some reason, which I don't remember now, all my docker containers had forbidden access to internet. HomeAssistant is fine with it but ebusd needs to download configuration files and it took me a while to find out why requests for configuration were failing.

The biggest issue was with configuration. My Wolf is not supported out of the box. Following docker readme, I have run the following command:

root@turris:~# docker run --rm -it -p 8888 john30/ebusd --scanconfig -d ens:192.168.1.87:9999 --latency=20
2023-09-03 18:07:50.453 [main notice] ebusd 23.2.23.2 started with auto scan on device: 192.168.1.87:9999, enhanced
2023-09-03 18:07:51.734 [bus notice] device status: resetting
2023-09-03 18:07:51.735 [bus notice] bus started with own address 31/36
2023-09-03 18:07:51.740 [bus notice] signal acquired
2023-09-03 18:07:52.240 [bus notice] device status: reset, supports info
2023-09-03 18:07:52.355 [bus notice] device status: extra info: firmware 1.1[380f].1[380f], jumpers 0x0f
2023-09-03 18:07:58.939 [bus notice] new master 71, master count 2
2023-09-03 18:07:58.939 [update notice] received unknown BC cmd: 71fe50180e0080008000800080008000800000
2023-09-03 18:08:02.009 [bus notice] scan 76: ;Kromschroeder;  ;0227;-
2023-09-03 18:08:02.009 [update notice] store 76 ident: done
2023-09-03 18:08:02.009 [update notice] sent scan-read scan.76  QQ=31: Kromschroeder;  ;0227;-
2023-09-03 18:08:02.009 [bus notice] scan 76: ;Kromschroeder;  ;0227;-
2023-09-03 18:08:02.219 [main error] HTTP failure: receive error: 404 Not Found
2023-09-03 18:08:02.219 [main error] unable to load scan config 76: list files in kromschroeder ERR: element not found
2023-09-03 18:08:02.219 [main error] scan config 76: ERR: element not found
2023-09-03 18:08:13.921 [update notice] received unknown BC cmd: 71fe50171000011a016b0200800080008000800080
2023-09-03 18:08:28.879 [update notice] received unknown BC cmd: 71fe50180e0080008000800080008000800000

I connected to docker shell and get more info:

root@600974f7960e:/# ebusctl i
version: ebusd 23.2.23.2
device: 192.168.1.87:9999, enhanced, firmware 1.1[380f].1[380f]
signal: acquired
symbol rate: 20
max symbol rate: 47
min arbitration micros: 4
max arbitration micros: 4
min symbol latency: 17
max symbol latency: 19
scan: finished
reconnects: 0
masters: 2
messages: 12
conditional: 0
poll: 0
update: 4
address 31: master #8, ebusd
address 36: slave #8, ebusd
address 71: master #9
address 76: slave #9, scanned "MF=Kromschroeder;ID=  ;SW=0227;HW=-"

Using HowTos and Message definition, I was able to decode above unknown messages:

2023-09-03 18:08:13.921 [update notice] received unknown BC cmd: 71fe50171000011a016b0200800080008000800080
2023-09-03 18:08:28.879 [update notice] received unknown BC cmd: 71fe50180e0080008000800080008000800000

root@7e8bde847891:/# ebusctl grab result
71fe50171000010301580200800080008000800080 = 2
71fe50180e0080008000800080008000800000 = 3

There is a master device (id 71) - that's the solar heating. Then there is a slave device (id 76) which is Wolf BM Solar module (it displays data from master). The master broadcasts (BC in log or fe in message) messages. PBSB of messages are 5017 and 5018.

I've searched through ebusd-configuration repo for PBSB codes and found them in ebusd-2.x.x/de/wolf/50.csv.

To be able to use updated configs, I've created ebusd_config folder on turris that is shared to ebusd docker container. Based on unable to load scan config 76: list files in kromschroeder error, I've created kromschroeder subfolder there where I

• copied ebusd-2.x.x/de/_templates.csv to ebusd_config/kromschroeder/_templates.csv
• copied ebusd-2.x.x/de/wolf/50.csv to ebusd_config/kromschroeder/76.csv
• copied ebusd-2.x.x/de/wolf/broadcast.csv to ebusd_config/kromschroeder/broadcast.csv and added 2 lines with missing PBSB codes (changing message type to broadcast b):
  

  # type (r;w;u;1-9),class,name,comment,QQ,ZZ,PBSB,ID,field1,part (m;s),type / templates,divider / values,unit,comment,field2,part (m;s),type / templates,divider / values,unit,comment,field3,part (m;s),type / templates,divider / values,unit,comment,field4,part (m;s),type / templates,divider / values,unit,comment,field5,part (m;s),type / templates,divider / values,unit,comment,field6,part (m;s),type / templates,divider / values,unit,comment,field7,part (m;s),type / templates,divider / values,unit,comment
  *b,broadcast,,,,FE,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
  b,,betrd,Betriebsdaten des Feuerungsautomaten an den Regler,,,0503,01,status,,UCH,,,Feuerungsautomatstatus,zustand,,HEX,,,Feuerungsautomatzustand,stellgrad,,percent0,,,StellgradKesselleistung (Wolf Gastherme Ersatzwert: FF),kesseltemp,,temp1,,,Kesseltemperatur ,ruecklauftemp,,temp0,,,Rücklauftemperatur ,boilertemp,,temp0,,,Boilertemperatur ,aussentemp,,outsidetemp,,,
  b,,sollw,Sollwertübertragung des Reglers an andere Regler,,,0800,,kesselsolltemp,,temp2,,,Kesselsollwert,aussentemp,,temp2,,,Außentemperatur,leistungszwang,,D1B,,%,Leistungszwang,status,,HEX,,,Status,brauchwassersolltemp,,temp2,,,Brauchwassersollwert,,,,,,,,,,,,
  b,,ertraege,,,,5018,,leistung,,D2B,,,Solarleistung,ertraglow,,UCH,,,ErtragTagLow,ertraghigh,,UCH,,,ErtragTagHigh,ertragsummelow,,UCH,,,SummeErtragLow,summertraghigh,,UCH,,,SummeErtragHigh,ertragsumme,,UCH,,,SummeErtragM,,,,,,
  b,,temp,,,,5017,,pumpe,,UCH,0xbc=off;0xbd=on,,SolarPumpe,,,IGN:1,,,,kollektortemp,,temp,,,Kollektortemperatur,wwsolartemp,,temp,,,WW Solartemperatur,,,,,,,,,,,,,,,,,,
  

I ran the docker again and success:

root@turris:~# docker run --rm -it -p 8888 -v "/srv/ebusd_config:/mnt:ro" john30/ebusd --scanconfig --configpath=/mnt -d ens:192.168.1.87:9999 --latency=20
2023-09-03 21:03:05.609 [main notice] ebusd 23.2.23.2 started with auto scan on device: 192.168.1.87:9999, enhanced
2023-09-03 21:03:05.853 [bus notice] device status: resetting
2023-09-03 21:03:05.854 [bus notice] bus started with own address 31/36
2023-09-03 21:03:05.873 [bus notice] signal acquired
2023-09-03 21:03:06.305 [bus notice] device status: reset, supports info
2023-09-03 21:03:06.473 [bus notice] device status: extra info: firmware 1.1[380f].1[380f], jumpers 0x0f
2023-09-03 21:03:15.326 [bus notice] new master 71, master count 2
2023-09-03 21:03:15.326 [update notice] received unknown BC cmd: 71fe5017100001e000430200800080008000800080
2023-09-03 21:03:16.113 [bus notice] scan 76: ;Kromschroeder;  ;0227;-
2023-09-03 21:03:16.113 [update notice] store 76 ident: done
2023-09-03 21:03:16.113 [update notice] sent scan-read scan.76  QQ=31: Kromschroeder;  ;0227;-
2023-09-03 21:03:16.113 [bus notice] scan 76: ;Kromschroeder;  ;0227;-
2023-09-03 21:03:16.115 [main notice] read common config file kromschroeder/broadcast.csv
2023-09-03 21:03:16.116 [main notice] read scan config file kromschroeder/76.csv for ID "", SW0227, HW65535
2023-09-03 21:03:16.116 [main notice] found messages: 8 (0 conditional on 0 conditions, 0 poll, 4 update)
2023-09-03 21:03:30.288 [update notice] received update-read broadcast ertraege QQ=71: -;0;128;0;128;0
2023-09-03 21:03:45.274 [update notice] received update-read broadcast temp QQ=71: 0;14.00;36.19

Data from master broadcast (temp QQ=71: 0;14.00;36.19) tells me that:

• 0 - pump is not running
• 14.00 - collector temperature
• 36.19 - warm water tank temperature

I'm not interested in ertraege (yield of the solar) - gathering is turned off anyway.

The final command to run ebusd in the background has to use environment variables to set the parameters:

docker run --name ebusd -d -p 9090:9090 -v "/srv/ebusd_config:/mnt:ro" -e EBUSD_DEVICE=ens:192.168.1.87:9999 -e EBUSD_SCANCONFIG= -e EBUSD_CONFIGPATH=/mnt -e EBUSD_LATENCY=20 -e EBUSD_HTTPPORT=9090 john30/ebusd

There are several options how to get data from ebusd to Home Assistant. As I don't use MQTT and I need just 2 values, I've decided to use simple polling via http (that's why EBUSD_HTTPPORT parameter in above command). I've tried to secure it by -e EBUSD_READONLY= but that resulted in failures of reading the configuration (which is actually expected as I have found later).

rest:
  - resource: http://192.168.1.1:9090/data/broadcast/temp
    scan_interval: 15
    binary_sensor:
      - name: Solar - running
        unique_id: solar_ohrev_id
        device_class: running
        value_template: "{{ value_json['broadcast']['messages']['temp']['fields']['pumpe']['value']|int == 1 }}"
    sensor:
      - name: Solar - collector temperature
        unique_id: solar_kolektor_id
        state_class: measurement
        device_class: temperature
        value_template: "{{ value_json['broadcast']['messages']['temp']['fields']['kollektortemp']['value'] }}"
        unit_of_measurement: °C
      - name: Solar - tank temperature
        unique_id: solar_teplota_vody_id
        state_class: measurement
        device_class: temperature
        value_template: "{{ value_json['broadcast']['messages']['temp']['fields']['wwsolartemp']['value'] }}"
        unit_of_measurement: °C

This is graph from today's sunny weather. It's nicely visible how the full tank was heated to over 60°C.

• red line - collector's temperature
• blue line - bottom tank temperature
• orange line - top tank temperature

Quest for lower electricity consumption - What does burn the heat?

Equipped with long term data, I started performing tests. As described previously, my home setup is not that simple.

Heating pipe for warm water tank is not separated from central heating pipes by three-way valve. When heating up the tank, the pump for tank circle runs and the other two are off. Vice versa when heating the central heating branches.

This is the usual temperature graph for a night (that means no warm water concumption):

From 65°C to 50°C in approximately 2,5 hours. The reason for not fully heated tank around 1:00 is there more expensive electric tariff between 1:00 - 2:00 and the boiler is turned off.

Hypothesis

My first idea was the water in tank is cooled by water from the central heating. So I closed valves for a night and checked the graph.

The cooling rate from 65°C to 45°C is the same as for any other night, so cooler water for the central heating is not the culprit. Why the tank cannot keep hot water longer was a mystery...

Culprit

Finding the real culprit required having a beer with neighbors in a pub. More head, the greater knowledge and soon we had a hypothesis that the loss of heat is caused by natural circulation. My warm water tank is in the basement and warm water pipes go through the house and returns to the tank. As pipes are relatively wide, they allow natural circulation. When I stopped the circulation, the graph looked much better. The loss was less than 15°C in 8 hours.

Now I just have to figure out what to do. With no circulation, it takes quite a long time to get warm water from the tap. With circulation, the cost of heating is high... 

My current idea is to use electric valve and open the circulation just for a while, probably speeding it up with a pipe.

Edit:

The real culprit was found when new tank was installed - the reverse flap was faulty and caused natural circulation. Once fixed, the warm water can circulate only in one direction again and there is no natural circulation anymore.

Quest for lower electricity consumption - Investigate Arduino Crash

As I wrote last time, my joy did not last long because the data flew only for 1-2 hours and then it stopped. I connected WeMos to my laptop and boiler and kept it running while logging the progress to serial monitor. Eventually, it crashed (full log):

11:21:19.141 -> --------------- CUT HERE FOR EXCEPTION DECODER ---------------
11:21:19.141 ->
11:21:19.141 -> Exception (0):
11:21:19.141 -> epc1=0x402010f4 epc2=0x00000000 epc3=0x00000000 excvaddr=0x00000000 depc=0x00000000
11:21:19.141 ->
11:21:19.141 -> >>>stack>>>
11:21:19.141 ->
11:21:19.141 -> ctx: sys
11:21:19.141 -> sp: 3fffebb0 end: 3fffffb0 offset: 0190
11:21:19.141 -> 3fffed40: 3ffefa44 3ffee748 3ffee740 401001e2
11:21:19.141 -> 3fffed50: 3ffe0000 3ffeec30 3ffee740 4010041b
...
11:21:20.500 -> 3fffff90: 3fffdad0 00000000 3ffee824 401004dd
11:21:20.500 -> 3fffffa0: 3fffdad0 00000000 3ffee824 40206906
11:21:20.500 -> <<
11:21:20.500 -> --------------- CUT HERE FOR EXCEPTION DECODER ---------------
11:21:20.500 ->
11:21:20.500 -> ets Jan 8 2013,rst cause:2, boot mode:(3,6)
11:21:20.500 ->
11:21:20.500 -> load 0x4010f000, len 3460, room 16
11:21:20.500 -> tail 4
11:21:20.500 -> chksum 0xcc
11:21:20.500 -> load 0x3fff20b8, len 40, room 4
11:21:20.500 -> tail 4
11:21:20.500 -> chksum 0xc9
11:21:20.547 -> csum 0xc9
11:21:20.547 -> v000604e0
11:21:20.547 -> ~ld

The problem was that although WeMos did somehow restart, it did not pass the step that connects it again to wifi and stuck there. I had to find why it crashed.

ESP documentation shows you how to deal with crashes. I've installed Arduino ESP8266/ESP32 Exception Stack Trace Decoder and ... nothing. I just could not find it in the menu. After searching through forums, I've found out it's because I use the new Arduino IDE v2 written in Node and the decoder is a Java plugin for Arduino IDE v1. There are some ways how to make it work with v2 IDE but for me the easiest way was to install IDE v1 (1.8.19). Finally, I had the stack trace:

Exception 0: Illegal instruction
PC: 0x402010f4
EXCVADDR: 0x00000000

Decoding stack results
0x401001e2: OPENTHERM::_writeBit(unsigned char, unsigned char) at C:\Users\lucen\Downloads\Arduino\thermona.el9/opentherm.cpp line 204
0x4010041b: OPENTHERM::_timerISR() at C:\Users\lucen\Downloads\Arduino\thermona.el9/opentherm.cpp line 169
0x401004f4: timer1_isr_handler(void*, void*) at C:\Users\lucen\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\3.0.2\cores\esp8266\core_esp8266_timer.cpp line 37
0x4010053c: timer1_isr_handler(void*, void*) at C:\Users\lucen\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\3.0.2\cores\esp8266\core_esp8266_timer.cpp line 44
0x40101340: _stopPWM(uint8_t) at C:\Users\lucen\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\3.0.2\cores\esp8266\core_esp8266_waveform_pwm.cpp line 264
0x40101340: _stopPWM(uint8_t) at C:\Users\lucen\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\3.0.2\cores\esp8266\core_esp8266_waveform_pwm.cpp line 264
0x40100750: __digitalWrite(uint8_t, uint8_t) at C:\Users\lucen\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\3.0.2\cores\esp8266\core_esp8266_wiring_digital.cpp line 87
0x401001e2: OPENTHERM::_writeBit(unsigned char, unsigned char) at C:\Users\lucen\Downloads\Arduino\thermona.el9/opentherm.cpp line 204
0x401004bc: ets_post(uint8, ETSSignal, ETSParam) at C:\Users\lucen\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\3.0.2\cores\esp8266\core_esp8266_main.cpp line 181
0x401004f4: timer1_isr_handler(void*, void*) at C:\Users\lucen\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\3.0.2\cores\esp8266\core_esp8266_timer.cpp line 37
0x401004f4: timer1_isr_handler(void*, void*) at C:\Users\lucen\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\3.0.2\cores\esp8266\core_esp8266_timer.cpp line 37

But I was not clever from it... What illegal instruction during sending data to boiler? It's worth to note my knowledge about C++ is almost zero and the same applies for Arduino/WeMos HW. So I was not really sure what I need to look for...

I've enabled all compiler warnings in IDE Preferences and saw a warning about ICACHE_RAM_ATTR deprecation in favor of IRAM_ATTR. I have updated it in OpenTherm library but program still crashed. So I continued to search through forums. 

Soon, I've found this StackOverflow question about ISR (Interrupt Service Routine) and why IRAM_ATTR attribute is needed. It did not ring the bell for me. Retrospectively, it should especially if I read it more carefully but I didn't and thus still not understand the issue. I just knew it has something to do with interrupts, functions not available in memory. Few hours forward and I found great blog post by Chris Dzombak: Debugging an Intermittent Arduino/ESP8266 ISR Crash. I had the same reset reason (rst cause:2, boot mode:(3,6)) and Chris explained his investigation so well that even I have finally understand it.

I've went through all functions that were called from OPENTHERM::_timerISR() method and add IRAM_ATTR attribute. I uploaded it to WeMos and ran it. It did successfully pass 2 hours timestamp. But it crashed again after about a day. Looking at the new crash I saw almost the same stack trace. I gave up and added IRAM_ATTR attribute to all private methods and public send method (code). Since then, the data has been flowing flawlessly for couple of days now, so it seems the problem has been fixed!