Simple LIN bus record/replay

[laserir]

Hi there,
very advanced hard- and software indeed! Very impressed!

I have a Truma Contol 4 Heater and Truma A/C operating with the Truma iNet Box and intend to switch the iNet Box for a custom solution, but much more basic.

First question: Have you already successfully reverse engineered the LIN protocol messages for control the Truma heater/A/Cs?
Second question: Which possibilities do you see/suggest to do the a simple record/playback solution? (Record the message e.g. sent when Heater is set on to xx °C etc. and simply playback to achieve exactly this operation.) With this I could save some hardcoded messages/presets. Is there some kind of shield or module (perhaps a RS485 or CAN bus module?) I could use to sniff the LIN bus and replay on this? Is the iNet box a Master and does is supply the power to the bus?

Thanks a lot in advance!

[morawekj]

We had some logging, manly are 5 Frames, and you have repeat them for kepp alaive.

CP Plus is LIN Master

https://docs.google.com/spreadsheets/d/16nw7vJGL2m406Nb3y3_9kxW-dGib02PLaZ2sJC5xSz4/edit?usp=sharing

A simple Saleae Logic Analyzer (Clone also do) will do the Job for logging

[laserir]

Thanks for the document! So I see the communication Heater<->Panel is on the bus. I was aiming for the iNet<->CPPlus connection. As I understand heater and a/c are connected to the CPPlus and there is a single connection to the iNet box, so I could feed commands into the system and keep the CPPlus panel. Any ideas?

EDIT: According to this (https://serviceblog.truma.com/de/2020/06/29/truma-inetbox-was-ihr-schon-immer-wissen-wolltet/#comment-107006) TIN1 is the bus where CPPlus is Master; devices on that bus (heater and A/C) will (and must) be found by the CPPlus to be usable in the app.
TIN2 is a bus only handled by the iNet-box (search devices via app, not CPPlus).
So my focus will be to be the client (which the iNet box probably is) in the TIN1 bus.

[laserir]

So... I got myself this —> https://www.microchip.com/developmenttools/ProductDetails/APGDT001

Do you know which line goes where on the TIN plug?
Vbat is from the 12V of the caravan I guess?

[laserir]

If any useful... attached the conversion of the room temperature sensor (PID 61).
https://docs.google.com/spreadsheets/d/1c9_FCGcBeeDjsJtaojFys3Nlx2V27TBXtvGYYBC2gCw/edit?usp=sharing

The analyzer just arrived, let's see where the journey takes us.

[betz]

very interesting. Thanks for sharing

…

On Tue, Mar 30, 2021 at 4:06 PM laserir ***@***.***> wrote: If any useful... attached the conversion of the room temperature sensor (PID 61). https://docs.google.com/spreadsheets/d/1c9_FCGcBeeDjsJtaojFys3Nlx2V27TBXtvGYYBC2gCw/edit?usp=sharing The analyzer just arrived, let's see where the journey takes us. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#10 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAB6XDMHQ4QM3FN36FFRB5TTGHLFZANCNFSM4ZTRQNRA> .

[laserir]

Also if useful... here some analyses with all devices connected (CPPlus + Heater + A/C + iNet Box) and without iNet Box, A/C respectively...
https://docs.google.com/document/d/1cXJOo0R7dj7mbHKq1hL0edU1fNbdmElGy7ql1EkBc-k/edit?usp=sharing
Seems as iNet Box does its magic with PID "D8" and A/C with PID "97".
"7D" fails if either device is disconnected.

Also I'm curious about the massive "3C" bursts (marked in blue). Maybe some auto-discover about the lost devices?

[betz]

could you, for the record, tell how you connected everything? The 'Microchip LIN Serial Analyzer Development Kit' to the cpplus? which port? Tempted to do the same. I was first thinking to control over sms automated, but the lin protocol would be nicer indeed.

…

On Tue, Mar 30, 2021 at 4:34 PM laserir ***@***.***> wrote: Also if useful... here some analyses with all devices connected (CPPlus + Heater + A/C + iNet Box) and without iNet Box, A/C respectively... https://docs.google.com/document/d/1cXJOo0R7dj7mbHKq1hL0edU1fNbdmElGy7ql1EkBc-k/edit?usp=sharing Seems as iNet Box does its magic with PID "D8" and A/C with PID "97". "7D" fails if either device is disconnected. — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#10 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAB6XDLHN5OKXUE4E5AGLU3TGHON5ANCNFSM4ZTRQNRA> .

[laserir]

could you, for the record, tell how you connected everything? The 'Microchip LIN Serial Analyzer Development Kit' to the cpplus? which port? Tempted to do the same. I was first thinking to control over sms automated, but the lin protocol would be nicer indeed.
…

The CPPlus is the TIN1 bus Master, iNet Box (TIN1 Ports) and devices acting as slaves.
On the TIN2 port, a separate Bus, the inet Box is Master. You should focus on the TIN1, as TIN2 is only used for in-app control.
Do not connect the CPPlus to TIN2, that would be 2 masters!

As it is a bus system, it doesn’t matter where on the bus you connect. Meaning you could connect to the TIN1 ports on the CPPlus or iNet box or even use a coupler like this:

https://www.conrad.at/de/p/train-modules-75124-rj12-4fach-verteiler-loconet-fertigbaustein-497092.html

The connection is done via RJ12 cable:
1 -
2 -
3 LIN
4 -
5 GND
6 -

Last connection is VBatt, meaning the 12V+ of the car battery.

[laserir]

CPPlus or iNet box or even use a coupler like this:

https://www.conrad.at/de/p/train-modules-75124-rj12-4fach-verteiler-loconet-fertigbaustein-497092.html

The connection is done via RJ12 cable:
1 -
2 -
3 LIN
4 -
5 GND
6 -

Last connection is VBatt, meaning the 12V+ of the car battery.

[morawekj]

We have also a Telegram Group for Truma Revere Engineering, if interestet, give me a note on Telegram @RFguy2

[amaral989]

Hello all,
I have been searching for a integration for Truma and home assistant ( open source home automation software)
Is this possible?
I'm do not code or a software engineer.
Looking for help, and willing to compensate

Thank you
John.

[7xy]

Hello all,

I have been searching for a integration for Truma and home assistant ( open source home automation software)

Is this possible?

I'm do not code or a software engineer.

Looking for help, and willing to compensate

Thank you

John.

Hi John, I realised it with Openhab 3. But I am sure that it will work also with Home Assistant which I use for reading my smart shunt. The only thing you need is a relay with a NO NC and a resistor with 10 kOhm. You just open one wire of your temperature measurement and now you can fake low temperature. So you can control your Truma heating via Home Assistant. To get an idea about this solution visit my blog under https://schleeh.de By the way I can not code either.

[amaral989]

Yes, I am familiar with the thermostat hack.
I was hoping to get more ability like controlling the hot water , or the blower fan as well.
The only way I can think of is to read and write the hex code and talk to it Via the LIN can bus.

[schwinn]

@morawekj I've update for the spreadsheet in "Frame Decoding 4.1". ID 22 D0 is the battery voltage in 1/10 Volt. Bit 0x20 of D1 is raised, when shore power is connected.

When sending data via id 7d (3d) to LIN master, the frames D6 and D7 seems to be a checksum in the data field. Have someone noticed this already?

Here are two switch off commands, which are almost the same. Only D6 and D7 of "03 22" is different, but the have both the same checksum FC again.

LIN READ 3C 3C 03 21 00 00 22 FF FF FF B9
LIN READ 7D 3D 03 10 29 FA 00 1F 00 1E 8B
LIN READ 7D 3D 03 21 00 00 22 FF FF FF B9
LIN READ 7D 3D 03 22 54 01 0C 32 0A 40 FC
LIN READ 7D 3D 03 23 00 00 00 00 08 07 CA
LIN READ 7D 3D 03 24 00 00 08 07 02 02 C5
LIN READ 7D 3D 03 25 00 00 00 00 00 00 D7
LIN READ 7D 3D 03 26 00 00 00 00 00 00 D6
LIN READ 20 20 AA AA AA 00 12 02 E0 0F DB
LIN READ 61 21 D6 9B BB 28 12 02 F0 0F 34

LIN READ 3C 3C 03 21 00 00 22 FF FF FF B9
LIN READ 7D 3D 03 10 29 FA 00 1F 00 1E 8B
LIN READ 7D 3D 03 21 00 00 22 FF FF FF B9
LIN READ 7D 3D 03 22 54 01 0C 32 0D 3D FC
LIN READ 7D 3D 03 23 00 00 00 00 08 07 CA
LIN READ 7D 3D 03 24 00 00 08 07 02 02 C5
LIN READ 7D 3D 03 25 00 00 00 00 00 00 D7
LIN READ 7D 3D 03 26 00 00 00 00 00 00 D6
LIN READ 20 20 AA AA AA 00 12 02 E0 0F DB

Changing D6 or/and D7 to something random and the CP Plus will ignore the command, even if the frame checksum is valid.

[danielfett]

The second checksum is calculated just the same as the LIN bus checksum, but over all bytes in the LIN Transport Layer message (starting with 54 01). The checksum byte itself must be set to 00 or be ignored for the checksum calculation.

Edit: I have not yet figured out what the first byte is for, but given your examples it does not seem to be a checksum over the content.