Manufacturer Specific Pids

[berntd]

Hello all,

What is the general concesus about manufacturer specific PIDs?

Should a manufacturer use a specific PID only once or should they be start at 8000 for each different model but actually do different things?

Example:

On model 0100,
0x8000 = LEFT_TURN.

On model 0200
0x8000 = RUN_TO_THEHILLS


or
On model 0100,
0x8000 = LEFT_TURN.

On model 0200
0x8001 = RUN_TO_THEHILLS



Kind regards
Bernt

[sblair]

Bernt,

Section 6.2.10.2 covers all this.

Manufacturer-specific PID’s shall be created in the range of 0x8000 – 0xFFDF. Uniqueness of PID’s in this range is accomplished by associating the PID with the Manufacturer ID found as the most significant 16-bits of the UID. PID’s in the range of 0xFFE0 – 0xFFFF are reserved for future uses of this standard.

Manufacturer-Specific PID values should be selected by choosing the appropriate category from Table A-3 and adding an offset of 0x8000 to preserve a logical organization.

A manufacturer shall not use the same manufacturer-specific PID value for more than one meaning within any products falling under a given Manufacturer ID.

So long and short of it is that you must assign different PID's for different messages between products. You can't re-use PID #'s for different functions.

[prwatE120]

Scott has cleary quoted the standard. Note that there are two SHALL statements and one SHOULD.

I have yet to see manufacturers follow the recommendation about selecting a category from Table A-3 and adding the offset of 0x8000, so please DO NOT make any assumptions ...

regards

Peter Willis

[berntd]

Hello,

Thank yopu Scott, Peter.

Ok, so the PID is unique to the manufaturer code and not the model code.
That is easy and makes sense.

I do not understand the adding of offset x8000 to a pid from table A-3.

Surely if table A-3 has something that fits, we should just use that instead of a cutom pid?


Kind regards
Bernt

[sblair]

Bernt,

Yes, if there is a public PID already defined that fits, you want to use it. The part about adding the 0x8000 offset for manufacturer-specific PID's is about categorization. If you notice, all the PID's are somewhat grouped by categories. The idea is to keep that same categorization where possible in the manufacturer-specific range too.