OBDII vs Proprietary protocols

[Conor]

Hi Guys,

I have been doing some research on diagnostics / programming for a little project and have a couple of questions somebody might be able to help out on.

While I know that for the most part, diagnostics and programming is via the OBDII port (SAE J1962) on modern cars. With OBDII having a standardised port and set protocol / set of defined messages etc, it looks like manufacturers piggy back on this port for their own proprietary systems also.

For example Star uses a fairly beefy (de)multiplexer to squeeze a lot more functionality through.

* Do all manufacturers have a (de)mux like MB Star has or do some of them? From looking online, it looks like some car brands have more straightforward systems - why is this?

* For systems that are more bespoke and merely using the OBDII connector as a means to connecting with the car, what protocols do they use to send the data? Are the typically proprietary or would the be in this list of signalling protocols?

Thanks for any assistance on this

Conor

 

[400ixl]

A lot of manufacturers are settling on CAN BUS for a lot of the messaging exchange these days. With modern cars where you are getting into IoT sensor then standards like IFTTT (If this then that) are also commonly being used.

 

[Conor]

A lot of manufacturers are settling on CAN BUS for a lot of the messaging exchange these days. With modern cars where you are getting into IoT sensor then standards like IFTTT (If this then that) are also commonly being used.

Ok, I understand. But isn't that more appropriate for general running and use of the car?

Maybe I am missing something here, but I am more interested in the more proprietary side of stuff. For example, what protocol/standard is the message between the OBDII port and the multiplexer of the Star box for example?

 

[400ixl]

ODBII is a physical standard as well as a software standard. Star if I am correct uses K Line, CAN BUS, ODB, DOIP and UDS protocols to interoperate with the systems within the vehicle.

The multiplexer allows the Star system to be able to switch between different analogue and digital protocols to interchange between these. So the protocol between the multiplexer and the ODBII port could be any of the supported protocols. The proprietary bit is where the Star / Xentry software and the multiplexer talk and switch between protocols.

Most manufacturers have some form of multiplexer for some of their features and may even run their own protocols. Not sure if Mercedes do the latter or not.

What are you trying to achieve would be the question I am most interested in. If it is to talk to CAN BUS systems only then you can do that with a USB to CAN converter. Multiplexers contain all of the different converters into one unit.

 

[Botus]

ODB is mainly for engine management diagnostics…. my car has a further 49 modules that all produce info out the diagnostic socket, as well as taking programming in

there's work in progress to deliver an industry std to programme these days called j2534 https://www.boschdiagnostics.com/pro/j2534-faqs (but then there's v1 and v2 with bm on to their own v3 I believe)
all manu use a multiplexer this one is one of the most flexible


http://www.tiecar.net/products.html#CANtieCAR3

https://www.scantool-direct.co.uk/unicarscan-bluetooth-obd-adapter-for-ios-android-and-windows.html

https://www.mycarly.com/en/

 

[Conor]

Thanks guys,

I am interesting in creating a relay for the data that comes out of the OBDII port.

Basically, to relay the data from the port over a network and then to the physical device such as multiplexer, decoder unit etc.

The idea being to remove the need for specialised hardware to be at the car, and could be placed in another location. i.e. Server room / cloud etc..

To relay, would use a simple device that plugs into the car and relays the car via smartphone connection / wifi.

 

[Conor]

ODBII is a physical standard as well as a software standard. Star if I am correct uses K Line, CAN BUS, ODB, DOIP and UDS protocols to interoperate with the systems within the vehicle.

The multiplexer allows the Star system to be able to switch between different analogue and digital protocols to interchange between these. So the protocol between the multiplexer and the ODBII port could be any of the supported protocols. The proprietary bit is where the Star / Xentry software and the multiplexer talk and switch between protocols.

Most manufacturers have some form of multiplexer for some of their features and may even run their own protocols. Not sure if Mercedes do the latter or not.

What are you trying to achieve would be the question I am most interested in. If it is to talk to CAN BUS systems only then you can do that with a USB to CAN converter. Multiplexers contain all of the different converters into one unit.

See my post above on what I am aiming for.

I understand about the general OBDII stuff, but I am more interested in the stuff required to code new parts etc. I know they use the OBDII port, but wondering are the transport protocols OBDII also, or completely proprietary?

Interesting to heard that the hardware actively switches between protocols based on what is being sent.

 

[LostKiwi]

Why not use a smartphone based app? No experience of it but Carly for MB works with Bluetooth dongles.
I don't think you'd really want to expose your OBD2 port onto the internet as it has the ability to recode keys etc.

 

[Botus]

Interesting to heard that the hardware actively switches between protocols based on what is being sent.

I don't think you could recover anything usable.... these guys play funny and mix and match and send stuff all at the same time

If you want the files, go find a friendly indie (they'll have them on a DVD and or buy a fake setup on fleabay all the data is on the drive.... what's missing from the exciting files is the ability to get at, unravel and install. Check out for merc what SCN means... although most people will have the update on there kit already the ability to use and write to the car only happens after an acceptable handshake protocol between the dealers paid for and registered kit has logged in to germany's servers and gets authorisation to programme the car.

if you want to learn to play buy a e89 3 series BMW, all the files and dealer diagnostic kit is out there with millions of people actively on forums sharing how to do it (and breaking their cars) they hacked the e diff about 2 years back

 

[Conor]

Why not use a smartphone based app? No experience of it but Carly for MB works with Bluetooth dongles.
I don't think you'd really want to expose your OBD2 port onto the internet as it has the ability to recode keys etc.

I'm wondering if I can centralise all the bespoke hardware required to program a car into one place, then just relay the signals from the OBDII port to that central location.

That Carly App does look good though.

I don't think you could recover anything usable.... these guys play funny and mix and match and send stuff all at the same time

If you want the files, go find a friendly indie (they'll have them on a DVD and or buy a fake setup on fleabay all the data is on the drive.... what's missing from the exciting files is the ability to get at, unravel and install. Check out for merc what SCN means... although most people will have the update on there kit already the ability to use and write to the car only happens after an acceptable handshake protocol between the dealers paid for and registered kit has logged in to germany's servers and gets authorisation to programme the car.

if you want to learn to play buy a e89 3 series BMW, all the files and dealer diagnostic kit is out there with millions of people actively on forums sharing how to do it (and breaking their cars) they hacked the e diff about 2 years back

I'm not really trying to recover/reverse engineer anything really. I understand about SCN alright, is that basically a validation service which signs the codes to say they are MB legit.

What is the "e89 3 series"? It looks like the e89 is a Z4?

 

[LostKiwi]

I think the only way you would do this would be using Xentry C4 or C5 multiplexer which connects to the laptop via WiFi. In theory the WiFi from the C4/5 could be routed out of the vehicle to a remote location. The earlier C3 multiplexer connects via serial cable.

 

[Conor]

I think the only way you would do this would be using Xentry C4 or C5 multiplexer which connects to the laptop via WiFi. In theory the WiFi from the C4/5 could be routed out of the vehicle to a remote location. The earlier C3 multiplexer connects via serial cable.

Agreed, but I am thinking of building a custom gateway device that take a connection from the car and then relays over the internet. Then on the other side of the internet there is another gateway device that has an OBDII port that the diagnostic device plugs into.

The reason I was asking about the other types of protocols is that I would like the gateway device to be agnostics and support all possible protocols.

 

[Botus]

to be frank, if you are asking here.... then you shouldn't be touching anything.

the only out come will be frustration and unrecoverable dead modules (and or further vehicle damage)

there are devices that do what you want for most vehicles (I posted one already http://www.tiecar.net/products.html#CANtieCAR3)... if a software engineer (who knows all about it and how to crack star and xentry systems for breakfast) then decides he needs to pay merc for the xentry connect to do SCN coding I think it answers the question on how far you will get on Mercedes cars.

The other big thing is merc software is different to almost everyone else... there's some 1600 customisation you can tweak on a BMW using your mobile phone and bimmer geek pro tool. https://www.bimmergeeksprotool.com/ But zero on a Merc. They don't have the same set up

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