Decode OBD data from ST-902

I've got the device added to Traccar and I can see some basic attributes (coordinates, ignition etc) but is it possible to get more OBD data (fuel etc)?

All the HEX codes that I see in my logs are binary and therefore unable to be decoded. Have I reached the limit of what I can do with this device in Traccar?

2021-01-06 14:31:02  INFO: [e5bd9a18: huabao > 82.132.246.98] HEX: 7e8001000501917163445400010045020000507e
2021-01-06 14:31:02  INFO: [e5bd9a18] id: 019171634454, time: 2021-01-06 14:31:00, lat: 55, lon: -2, course: 41.0
2021-01-06 14:31:32  INFO: [e5bd9a18: huabao < 82.132.246.98] HEX: 7e020000830191716344540046000000000000000a032e8b4b001db7d400040000002921010622313001040000000fcc143839343431313030363833363937313038363346300117800100810200008202007583010084012885020000860128870200008801008901008a0200008b115756575a5a5a314b5a42573334343338338c04000000008d0200008e0100a000127e

I've found other similar topics on the forums but there doesn't seem to be a resolution.

You can check the decoder class to see what parameters are currently supported.

Thanks for your reply! Could you possibly link me to some documentation on how to do that?

Ah you mean the Java class in code for the protocol I'm using ?

Yes, I meant Java class.

I can't see any reference in that class to the attributes I'm talking about.

When I look at my device in the software provided by the device manufacturer these are the OBD fields I can see. You can also see things like vehicle faults etc.

Is it possible to add these extra attributes? I'm happy to do the work (although I'm not a Java dev) but if you can tell me if it's possible then I can put the time in.

Of course it's possible. Not sure where you looked, but after a brief look I can see that it already supports at least engine load and coolant temperature.

I looked here but yes sorry you're right it does have those but I'm pretty sure it's missing some things or maybe I just can't read!!

Anyway, so if it supports those things, how come I can't see them as state attributes in the UI?

Well, it's hard to miss if you just do a text search in the file:

https://github.com/traccar/traccar/blob/master/src/main/java/org/traccar/protocol/HuabaoProtocolDecoder.java#L295-L296

Sure, but I didn't search for those, I searched for the first few in the screenshot I sent (engine rotate, battery voltage) and didn't find anything so I assumed the others weren't there. My bad!

For the ones that are there, how can I view them in the traccar UI? According to that Java class I should be able to see engine load etc but I can't.

You should be able to see them in the state panel and in some reports.

If you don't see them, it could be one of the two reasons:

• Your device doesn't report that information
• Protocol format is different from what's currently implemented

I can't see them in the state panel or reports and I'm pretty sure the device does report those things because I could see them in the device manufacturer's software.

If the protocol format is different, what's involved in solving this? As I said before, I'm interested in contributing but it would be useful to have some guidance as a starting point.

You already know which file to change. That's a good starting point. You can add a sample from your device to the unit tests for verification.

I would also recommend you do a manual breakdown of a message to make sure that all the information is there before you start any coding.

Awesome, thanks! I think I can manage updating the unit tests with my HEX codes and seeing what comes out etc but I'm not sure how to do a manual breakdown of a message. Is the message you're referring to the same thing I linked at the beginning of this topic where the hex decoder couldn't decode because it's binary?

Yes.