Question about TTL to M-BUS adapter

[micmoc95]

Hello !
I bought the adapter you mentionned from Aliexpress.
It’s not clear to me how to connect it. Has the Vin pin to be connected to the ESP32 board or is the adapter powered from the M-BUS ? What is the jumper used for ? Which pins do I have to connect to my heater as the adapter seems to have two M-BUS connections.
Thanks for your answer.

Regards

[meks007]

ESP8266 RX is 17, TX is 18

TSS721 RX to ESP8266 TX
TSS721 TX to ESP8266 RX
VIN to either 3V3 or 5V
GND to GND

Pick one of the 2 MBUS pairs, either MB A or MB B

[micmoc95]

Thanks à lot ! What about the jumper and the four connections to M-BUS ? Regards Le jeu. 23 janv. 2025, 16:49, meks007 ***@***.***> a écrit :

…

ESP8266 RX is 17, TX is 18 TSS721 RX to ESP8266 TX TSS721 TX to ESP8266 RX VIN to either 3V3 or 5V GND to GND — Reply to this email directly, view it on GitHub <#5 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ADC6JMPA2DO2ENM2D7QPTFD2MEFQ3AVCNFSM6AAAAABVXJ4U52VHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDMMJQGE3TENZTGA> . You are receiving this because you authored the thread.Message ID: ***@***.***>

[meks007]

check github. i updated my comment.

[micmoc95]

OK thx

[micmoc95]

Hi !
I connected my Vitotronic 200 to MB_A and MB_B.
Using a terminal emulator with parameters 1200 bauds even parity 1 stop bit gives me strange values mostly FF, EF, FD, ... a lot of high values.
Do you think adapter may be faulty ? Any idea ?
Thanks for your help. Regards

[meks007]

cant say what you are doing. you're supposed to connect the adapter to the esp, mbus to the adapter. you need to flash the esp using the correct settings in configuration.h. communication should start as soon as you power on the esp, assuming your config is correct.

[micmoc95]

ESP is working fine. The issue is that the adapter’s ttl output sends wrong data. Either à heater problem or adapter issue.

[dumpfheimer]

Where are you getting the values from? (FF EF FD..)

[micmoc95]

Just at the TTL output of the M-BUS to TTL adapter. Using a terminal emulator I’m able to monitor this serial output.

[dumpfheimer]

I believe that is not a valid heater->vitotrol message

[micmoc95]

That’s actually my problem. Either my boiler has an issue - althought my Vitotrol 200 is workink fine - or the adapter is faulty .... or I’m missing something.
I don’t have an oscilloscope to check km-bus behaviour.
Is it OK that my boiler sends data constantly as soon as I power it on ?

[dumpfheimer]

Have you actually tried using WiFiVitotrol?
The heater sending messages repeatedly is fine. It's probably just looking for devices

[micmoc95]

For sure and it’s working fine. Thanks for this valuable work.
But it sees heater as not connected not surprising as it does not read correct messages.

[dumpfheimer]

I would not call that working fine if it's seemingly not working at all :)

So you have a vitotrol 200 and want to replace it with WiFiVitotrol, is that correct?

[micmoc95]

I’m not full time at this home so I want to add WifiVitrotol to my Vitotrol 200 to allow remote access.

[dumpfheimer]

I am afraid you will not be able to use both at the same time. The protocol is too simple for that. You would need to replace the vitotrol or switch before you leave.

You might be able to find some quirky workaround using multiple heating circuits (Heizkreise) because it let's you have one remote per circuit.

[micmoc95]

Thx for the advice. I can forget about Vitotrol if I manage to control the heater using HomeAssistant.
But I have to find an operational interface. Guess I will send back this one to Aliexpress.

[meks007]

what heater do you have and what device id does your heater return when you poll 8 bytes at address 0xF8?

[dumpfheimer]

I am not convinced that the converter is faulty although I can not be sure. I would expect it to not work at all or produce random garbage if something is wrong.

[micmoc95]

I have a Viessman Vitotronic 200. I can’t get any information as all I get does not seem to match KM-bus protocol. Similar output at each powering on of the heater:

09:58:00.984 Connected to CH34x device
09:58:00.985 00 FF FF ED FD FF F7 FF BF BF FD FD FF F7 FF BF BF FF BB EB ED FD FF F7 FF FD FF FF FB FD FF F7 BB B7 FF FF BB EB FB FD FF F7 BB B7 FB EB FB FD FF F7 BB B7 FF FF FB FD FF F7 EF BB BF FF BB EB FB FD FF F7 FF BF FF BB EB FB FD FF FF FF BB EB FD FD FF F7 5F BB F7 FF FF FD FF F7 5F BB F7 FF F7 FF FF F7 5F BB FD FF BB EB FF FF DD FD FF BB EB FB FF DD FD FF BB EB FB FD FF FD FF BB EB FB FD FF F7 77 ED FF FB EB FB FD FF F7 77 ED FD FF BB EB FB FD FF F7 77 BB FF FF FD FF F7 77 DB FD FF BB EB F7 FD FF F7 F7 FF FD FF BB FF FF F7 77 DB FD FF BB EB FD FD FF FF FF FD FF BB EB FD FD FF F7 BD FD FD FF BB EB FD FD FF BF FF FD FF F7 ED F5 BF FF F7 FD FF F7 ED F5 BF FF BB FD FF FF FF ED F5 BF FF FD FF D7 75 BF FF BB EB EF FD FF FF FF FF FF BB EB EF FD FF F7 7B BF FF FF BB EB EF FD FF F7 7B FF FF FF BB EB DD FD FF F7 FD FF F7 FF BB EB DD FF FF F7 FF BB EB DD FD FF F7 FD FF F7 FF BB EB DB FD FF F7 FF BB EB DB FD FF FF FF FF FF FB FD FF F7 BF F5 F7 FF BB EB FB FF F7 DD F7 FF BB EB DB FF FD F7 FF F7 FF FF F7 F7 DD F7 FF FF FD FF F7 FF AD F7 FF BB EB FD FD FF F7 FD F7 FF BB EB FD FD FF F7 FF AB F7 FF BB EB FB FD FF F7 6D EF F7 FF BB EB FB FD FF F7 FF FD FF F7 6D EF DF FF BB EB FD FF EF FF FF FD FD FF F7 F7 6F DF FF BB EB FD FD FF F7 F7 FB FF FF BB EB EF FD FF F7 BF 77 DF FF BB EB EF FD FF DF FF BB EB FF FF BF 77 BF FF BB EB FB FF FF F7 BF FF BB FD FF F7 EF BB FD FF BB EB FD FD FF DD FD FD FF F7 6D EF FF EB FD FD FF F7 6D EF DD FD FD FF F7 6D EF DD FF BB EB FB FD FF F7 F7 F7 FD FF BB EB FB FD FF F7 F7 EB DD FF BB EB FB FD FF F7 FF FB EB FB FD FF F7 BF D7 DD FF BB EB FB FD FF FF FF FB EB FB FD FF F7 BF D7 DD FF BB FD FF F7 6D EF
09:58:42.983 Disconnected

09:58:43.899 Connected to CH34x device
09:58:52.340 FF BF FF BB EB ED FD FF FF FF BF FF BB EB ED FD FF F7 FF FF BF FF BB FF FF FF F7 FF BF BF FF BB EB FB FD FF FF FF BF FF BB EB FB FF F7 BF FF BB EB FB FD FF BF FF BB EB FB FD FF FF BF FF F7 FF FF F7 EF BB FF FF FB FD FF F7 EF BB F7 FF BB EB FF FF FF BB F7 FF BB EB FD FD FF F7 5F FF FF FF BB EB FD FD FF F7 5F BB FF FF BB EB FB FD FF F7 FF DD FB EB FB FD FF F7 FF DD FF FB FD FF F7 FF DD FD FF BB EB FB FF FF ED FD FF BB EB FB FD FF FD FF BB EB FF F7 ED FD FF BB EB F7 FD FF F7 F7 FF FD FF BB FF FF F7 77 DB FF FF BB EB F7 FD FF F7 77 DB FD FF FF FD FF F7 BD B7 FD FF BB FD FF F7 BD B7 FD FD FD FF F7 BD B7 BF FF BB EB EF FD FF F7 ED FF FF FF BB EB EF FD FF F7 ED F5 FF BB EB EF FD FF F7 ED F5 FF FF BD ED EF FD FF D7 75 BF FF FF FD FF F7 7B BF BF FF BB EB EF FD FF BF FF BB EB FF FF 7B BF F7 FF BB EB DD FF FF FF FF FF FD FD FF F7 FD FF F7 FF BB EB DD FF FD FF F7 FF FD FF F7 BF F5 FB EB DB FD FF F7 BF F5 FF FF FB FD FF F7 BF F5 FF FB EB DB FD FF F7 F7 DD FB DB FD FF F7 F7 DD FF FF BB EB DB FD FF F7 F7 DD F7 FF BB EB FD FD FD F7 FF BB EB FD FD FF F7 FF BB FF FF F7 FF AD FF FF BB EB FB FD FF F7 6D EF FF EB FB FD FF F7 6D EF F7 FF BB EB FB FD FF FF FF DF FF BB EB FD FD FF F7 EF FF FF FD FD FF F7 F7 6F DF FF FF FD FF F7 F7 6F FF FF EF FD FF F7 BF 77 EB EF FD FF F7 BF 77 FF FF BB EB EF FD FF F7 BF 77 BF FF F7 FF FF F7 BB B7 BF FF BB EB FF EF BB FB EB FD FD FF F7 BD B7 DD FF FD FF F7 6D EF FD FF BB EB FD FD FF F7 6D EF DD FF BB EB FD FD EF DD FF BB EB FB FD FF DD FF FD FF F7 F7 EB DD FF BB FD FF FF F7 EB DD FF FF FD FF F7 BF D7 DD FF BB EB FB FD FF FF FF EB FB FD FF F7 BF D7
09:59:09.639 Disconnected

[micmoc95]

I’m wondering if my 10 years old heater could use a different protocol like opentherm ?

[dumpfheimer]

I am afraid vitotrol and vitotronic are two different product lines and might very well use different protocols.

[meks007]

if it's anything like what's mentioned in the manual then it uses a completely different addressing scheme and would support your theory that it's not even speaking KM-Bus

https://community.viessmann.de/viessmann/attachments/viessmann/customers-oil/9289/1/Serviceanleitung%20Vitotronic%20200%20KW1.pdf

[micmoc95]

In the documentation vitotronic 200 ko1b comes with vitotrol 200a. KM-bus is mentionned several times.
What kind of heater did you test your project with ?

[dumpfheimer]

Very interesting. I too would read the documentation as if the vitotrol 200 should be compatible.

So just to be clear. You do not have a vitotrol 200 currently connected? Is your heater set up to have the remote control enabled?

If not it might just be communicating with another device connected via km bus.
Did you follow the instructions as if you were installing a vitotrol 200?

To answer your question I have a vitocal 200s

[micmoc95]

My heater is located in my secondary house I just bought and is about ten years old. Vitola (heater)/Vitoflam (burner)/Vitotronic 200 KO1B is wirely connected to Vitotrol 200A and fully operational.
I captured data replacing Vitotrol connection on first 145 plug and then with Vitotrol connected on first 145 plug and adapter on second 145 plug - same results.
Maybe I should open Vitotrol device and see which chipset is used inside.