CANbus wiring on LF Bros diesel heater

[cheesegas]

Hi all. Recently serviced by LF Bros (one of the better made and supported Chinese/Czech ones) blown air diesel heater, and noticed there's a white connector off the controller board I didn't see before and it's not mentioned in the manual.

 

Reading the silkscreens on the board, it looks like this is a CANbus connector which is interesting! Long shot but has anyone seen a similar heater with CANbus which has this feature mentioned in the documentation? I expect it's a fully working feature as the PCB is fully populated with a CANbus driver IC and all components. Webasto and Eber both have CANbus connections too, marketed under various names.

 

I have a CANbus analyzer in storage so if there's no info on this, over winter I'll hook up it up and see what messages it spits out. Assuming it's vaguely ISO 11898 compliant, I'll try and throw some frames at it and see what happens. End goal is to get it to talk to the Cerbo so I can build a better remote start - currently it's hooked up to a spare heater remote and some relays.

 

(also, I was running this on the lowest setting for many hours in spring so was expecting there to be considerable carbon buildup and a clogged atomiser mesh, but it was all very clean inside - a bit of grey-brown deposit in the combustion chamber but that's it, barely enough to wire brush out)

[BEngo]

Nicknorman is the forum's Canbus/Empirbus wizzard.  I am sure he will be along.

 

I think your lack of  carbon build up is down to the long hours of running.  Problems usually occur when the burner is short-cycling because either the heat output is too great to be tolerated by the user, so it gets turned off before the burner has run long enough that it has cleaned up  or because the system is inadequate to disperse the heat, so the boiler protection turns it off.

 

N

[cheesegas]

5 minutes ago, BEngo said:

I think your lack of  carbon build up is down to the long hours of running. 

Thanks, good insight. It's run for around half an hour in the morning on full power, and then the low power periods are usually overnight so that would explain it. I never switch it on low power and then switch it off again a short time after, and the controller is set to constant output mode rather than thermostatic.

[nicknorman]

Sorry, no idea about canbus on a Chinese heater! I think the analyser will be the way to go, but even then it may just reveal output data and not any input commands that it might be able to receive.

 

And of course there is no guarantee that just because there is a canbus interface chip, there is also the firmware to support it. But I suppose activity vs no activity on the canbus will answer that question.

[Quattrodave]

I came accross this a while back (I didnt write it, I can't take any credit), might be just what you're after... A few pages in it analyses the communications protocol...

 

Hacking the Chinese Diesel Heater Communications Protocol V9.docx

Edited October 1, 2024 by Quattrodave

[cheesegas]

16 hours ago, nicknorman said:

And of course there is no guarantee that just because there is a canbus interface chip, there is also the firmware to support it. But I suppose activity vs no activity on the canbus will answer that question.

Yep, that's my thoughts - it may have been added for a future firmware revision or the same board used across multiple heaters with different features. I'm holding hope as it's silkscreened CAN H and CAN L on the PCB. When I get bored in winter I'll hook the analyzer up to it.

 

14 hours ago, Quattrodave said:

I came accross this a while back (I didnt write it, I can't take any credit), might be just what you're after... A few pages in it analyses the communications protocol...

Thanks, that's really interesting! However, it discusses the protocol between the controller and the heater itself which looks to be proprietary - my heater has a different main board to all other Chinese diesel heaters, there's a little white connector coming off the harness which doesn't connect to anything and isn't mentioned in the manual. This is separate to the data connection between controller and heater.

 

That's the one I traced back and am hoping it's CANbus controllable, like Webastos/Ebers. 

[Quattrodave]

Ah, sorry i mis understood you, serves me right for scan reading... Time to breakout the canbus sniffer then 😁 Interesting little project, keep us in the loop 👍

Edited October 2, 2024 by Quattrodave

[MatthewJ]

Hi All, i'm working on decoding the LF Bros protocol as well but haven't made much progress. Have you figured out the baud rate? There's where i'm stuck as I don't have an spectrum analyzer to figure it out. 

[Quattrodave]

My guess would be 4800

 

Although I do wonder what your trying to do & with what device...

Edited February 17 by Quattrodave

[jonathanA]

9600  8 bit no parity was always the default setting for V24/RS232 just showing my age as i'm sure thats of no relevance to canbus. 🙂 

 

i'll get my coat. 

 

 

[Quattrodave]

What are you trying to achieve and on what device??

[nicknorman]

CANBUS tends to use different bit rates from the RS232 “doubling” series. I would expect 125Kb/s, 250Kb/s, 500kB/s, 1Mb/s. But it could be anything. Do you have an oscilloscope? In which case you should be able to see the bit rates. You don’t need a spectrum analyser.