Zehnder/Stork WHR Ventilation Unit

[wichers]

@rrozema, if you want to make it easy for yourself get a "db9 breakout connector" and a USB to RS232 DB9 converter. Then find yourself an Ethernet cable and connect it like this (TX/RX is from comfoair perspective):

[rrozema]

Thank you, I have ordered a max232 + db9 connector breakout board plus a db9 male connector so I can try it again using + and - 12v levels.

In this thread it is very hard to find any definite information on what exactly the connection type used by the Zehnder units is. Some say it's rs232, others claim it's rs485, some say it's ttl level and most people that have it working don't say anything at all about what protocol or components they use. And yet others fail to state what type of Zehnder unit they have (there could be different protocols used over different models?). If it is rs485 that my WHR930 Basic uses, (which I personally think would make sense looking at the descriptions of rs232 and rs485 and the intended use of the connection) will that max232 breakout board still work if it is rs485 and not rs232? I also have some usb <-> rs485 converters from my tests, so if I could use the same breakout board with those converters, that would be handy Or would that require another converter like this??

I am going to try again using the usb-serial converter into rpi method once I receive these new components. But it's from aliexpress (it's still only a hobby), so it will take a couple of weeks before I can continue this.

I would also like to try and reproduce your method with the microcontroller. I already have mqtt setup and running for an esp32 switch (plus a HDMI-CEC-bridge I no longer use). Can you share which components you used and how you wired these together? It doesn't have to be anything fancy, a component list plus a picture of a simple pen or pencil drawn schematic will do. As long as all the components are in there, plus how they're wired together. I did do some experiments with esp32 and other micros in the past, so I have some wemos, arduinos, nanos, esp32's etc lying around. But the problem is I'm more of a software man, not an electrician: I can reproduce a circuit from a schematic, but I'm hardly able to check levels, let alone make corrections if something is wrong or incomplete.

[wichers]

That integrated max3232 is a great buy!

There is indeed too much confusion on this as TTL has been mentioned in this thread. The Zehnder manuals are clearly stating if it's RS232 or RS485. You'll be fine as our WHR 930/950 units are definitely equipped with RS232. (https://zehndernl.zendesk.com/hc/nl/art ... 0001309769). Confusion probably comes from some of the "Luxury" units that are equipped with RS485 as well.

That ESP32 of yours should work perfectly. My setup consist of a 3.3v DC-DC Step-down Buck (rated higher than actual consumption) Converter + esp8266 + MAX3232, basically something like this: (but of course fed with 24v):

schematic.png (29.14 KiB) Viewed 2837 times

Once you get it working you could try to install esphome and use the yaml supplied in my project. Of course you initially need to flash the esp32 with esphome from a serial ttl device, plenty tutorials are available on this. Let me know how this works out.

[broekp]

I have been trying to figure this out for some time now.
Trying to move from a rpi with usb2serial dongle to esp32/esp8266 based setup but it just wil not work.

I am using a Tzt MAX3232 RS232 Serial Port Ttl Converter Module DB9 Connector MAX232 For Arduino
and and ESP32 and have tried different settings, different ports but the WHR930 does not accept the commands or give response.
I see that the commands sent by the module are correct (the same as the rpi is sending) but the WHR unit does not respond or repl.
I have now also tried your (wichers) code for ESPHome but using the same hardware this also does not work.

I am now wondering if the voltage levels are ok when directly connecting this module to ESP32.
Anyone know if wiring up the serial port converter directly to 3v3 from ESP32 will give right levels for WHR930 or does is need the 12v level?

I would appreciate any help as this is driving me nuts for weeks now.

[skle]

@rrozema. I have exactly the same issue as you describe. Tried switching RX/TX on the RS232 cable, but did not help. Re-checked all the wiring multiple times, but without success. The windows software from Stork cannot make a connection with the WTW Unit (WHR930 Basic). It finds the com port, but nothing more. Did you make any progress after your last post, or are you still waiting on your order from AliExpress?

[rrozema]

Still waiting

[broekp]

Ok, i solved my issue with the serial not working.
I think the male-male db9 connector is wired 1:1 and thus not giing correct pinning on my modified rj45 to rs232 cable.
Removed that one and made a new cable and it started working.

Looking at the examples above at least has helped me to understand more about this.

Especially the code for esphome from wichers has helped a lot.
Now trying to figure out how to add a fan control that will set the level. Will monitor the github and start to invetigate the logs to see how to do this from the comfoair component.

[anixi]

hi all, struggling with connecting the WHR 930 to my RI. I am using a R232 TLL-USB connector into the USB port of the RI. Unfortunately, cannot read it with the domoticz/mqqt scripts described here. IT seems that everybody here has have problems to start, can somebody help me?

[michdundee]

I have spent another sunday on this and I think I have to admit defeat: my WHR930 won't talk to me. I don't know what is wrong, but I've tried everything I can thik of and read here in this thread and it never responds.

I have the same problem (WHR 950 II) with the exact same board layout as yours. I thought I had blown my port as well, so I replaced the PIC18F6622 and reflashed it with a PicKit2. Turns out it almost impossible for a pic18f to lose functioning ports and still have a working cpu.

As I've already dumped the firmware (I have version 1.4) https://pastebin.com/gy97ntD0 I thought I would do some reversing to see if there is actual uart code implemented. Good news there is, I have also verified that the baudrate is set to 9600. To be continued..

Hi wichers, I would like to contact you since I need your help for some tips on esphome custom components creation? where can I contact you directly?
thank you in advance.
BR,
Michele

[DickNL]

Hello everyone, I am stepping into this topic as a Newbie. I have a WHR930 and want this wired up to my Pi/Domoticz.

Weird: The controller board of my WHR930 does not have a RJ45 but a RJ10 (8mm width) with 4 contacts, see photo. (telephone receiver cable plug)
Which pin layout should I use? Yes, the connector is RS232, as the text on the PCB states, see photo.
An RS232/RS485 to USB lies waiting for deployment on my desk...
Kind regards, Dick.

[smooc]

In case anyone passes by researching how to connect your Stork/Zehnder in this old topic.

There are several versions of the WHR 9X0. Particularly there is the Basic version and the Luxe version. For us the main difference is that the Luxe version features a DB9 serial RS232 connector. The Basic version uses a RJ42 connector. Note that both are RS232 12v/-12v (actually around 20v, which is within the range of the RS232 specs). If connecting to ESP or a Raspberry you will need to convert this to TTL levels which is " 3. 3v"/"- 3. 3v" (weird formatting due to forum software being obnoxious). You need to be careful what you buy. The cable to connect is not of standard wiring and you cannot buy one - afaik - off the shelve. You will need to do some cable cutting. Eg. you can buy a RJ45 CAT5 cable plug it in and cut it on the other side.

Note: some versions use the RS485 protocol. Which is half-duplex only. It will be stated on the port what it uses.

It seems that the WHR units are picky on the voltage levels provided by TX/RX. For example that meant for me that couldn't use the Tzt MAX3232 RS232 converter and I had to use a FTDI one. Mind you The FTDI and Max3232 were able to 'talk' to each other, but the Max3232 wasn't able to connect to the WHR (with adjusted wiring). I haven't found out why yet and I am eager to replace my Raspberry with an ESP.

In case someone has fried their WHR930 PCB, I have a brand new one for sale. Overstockage

[mayman]

Hi everyone, I have air whr 930 basic and I followed this page https://github.com/LukasdeBoer/esp8266-whr930-mqtt to control it. I get the readings and I can control comfortable temperature however I can’t change ventilation level. Any idea what can be the reason?
The display doesn’t use rj45 cable. Normally I control ventilation level from kitchen through 3 levels rotate switch.

Thanks a lot!

[waltervl]

Hi everyone, I have air whr 930 basic and I followed this page https://github.com/LukasdeBoer/esp8266-whr930-mqtt to control it. I get the readings and I can control comfortable temperature however I can’t change ventilation level. Any idea what can be the reason?
The display doesn’t use rj45 cable. Normally I control ventilation level from kitchen through 3 levels rotate switch.

Thanks a lot!

This does not seems to be a Domoticz issue, better make an issue on the repository https://github.com/LukasdeBoer/esp8266- ... qtt/issues