Automotive and Embedded Networks

cancel
Showing results for 
Search instead for 
Did you mean: 

Read out from OBD-II Freematic Emulator using ELM327 with USB and LabView

Hello Mark

Thank you for your nice reply. Blathering is OK when the blathering is informative:) The ELM327 adapter supports 12 different protocols and one of them is the SAE J1939. The ELM329 adapter also supports some extra protocols called "USERX CAN" which probably handle raw CAN functions. Why do you think I should start with handling raw CAN functions? Is it a easier way to go and is the documentation better?

 

I think that maybe the way to go now is to use my ELM327, which supports J1939, and get the J1939 standards document trying to get familiar with it, but maybe I'm wrong. I'm newbie to this kind of project. 

Paal

0 Kudos
Message 11 of 12
(3,557 Views)

Good morning Paal,

Being able to RX/TX raw CAN bus traffic has several advantage:

 

-J1979 traffic represents only a small portion of the network frames present, and is relatively cumbersome to use, although flexible from one vehicle to another. Many parameters are also not supported. For example, I did the most work with J1979 for a project on hybrid vehicles, and no pertinent hybrid info (SOC, traction current,battery cell temps or voltages, etc) was available without eavesdropping from raw traffic. Most manufacturers are hesitant, if not fully unwilling, to share their full traffic breakdowns without a decent outlay of cash, but if your company has cooperation from OEMs or a government agency that might be in the cards.

 

-The proprietary messages from or to the ECU would likely be unavailable without the ability to handle raw CAN.

 

-If you are involved in system design or diagnosis the ability to view all present message IDs is very helpful. Verifying that all nodes are transmitting correctly, verifying timestamps, and checking for bus errors, is also a plus.

 

-Understanding how data bytes are packaged in the frames themselves is very useful, and ultimately will pay dividends when learning another CAN based system.

 

You can still do useful things with only access to abstracted J1979 or strictly J1939 messages, but you'll probably soon be limited by using only those formats. The best of both worlds would be raw CAN with database support for both 1939 and 1979.

 

Good luck over there,

Mark

 

 

0 Kudos
Message 12 of 12
(3,548 Views)