Free Form CAN messages

Follow

John Kelsey

• March 06, 2020 11:33

Hi, 

I'm trying to add some free form CAN messages to a config to allow me to read some data from a CANopen ECU data stream.

I have the CAN data sheet the ECU manufacturer gives, see below

I have captured the CANbus data the ecu is putting out using the config supplied by EC for displays, see below

I have watched the free form can message video a number of times, https://support.enovationcontrols.com/hc/en-us/articles/360043350993-2-4-Free-Form-CAN-CANopen-

I have tried to add messages to the CAN port, screen shot below

I used the PID as the PGN on this version, which I'm sure is wrong. I think one of my problems is a lack of a PGN, can you have a PGN of 0 as the capture suggests or is the capture wrong about this?

The reason for the multiple variables was to put these all screen and see if I could get the separate bits of data on screen. My on screen text gauges are all greyed out. I was trying to show the data in bytes 0-8 for the PID 0x00002001. i.e MAP, Kpa Lambda x 1000, KPH x 10, Oil P Kpa

I also don't understand the PDU-S going into the PGN 

The ECU manufacturer also has a .dbc file which I can't open, is this any use to me? Should I spend time finding out how to read this information?

Thanks for any help you can give

John

0

• 

  Jeff Paluck

  • March 06, 2020 16:27

  John,  in the Frame ID section of the free form data message window, use the value "2001" or "00002001" instead of 200101. That Frame ID value is the complete 29bit ID of the message.  According to your capture, the ECU is sending the IDs 0x00002000 - 2007, so those are the ones you need to plug into that field.

   

  It doesn't look like a standard CANOpen or J1939 set of messages, but the display should still be able to pick up the messages.

  0

  Comment actions Permalink
• 

  John Kelsey

  • March 06, 2020 17:35

  Hi Jeff, 

   

  Again thanks for the reply.

  I had actually managed to figure that out after a bit more head scratching. I think I understand a little bit more now how the PGN is formed.

  Anyway I have the data being transmitted to the display now which is great. The spec from the ECU manufacturer is all over the place but by doing various captures I think I have found most of the variables I need although some of them are too high, or the wrong units or something! 

  Once I had the PGN correct I was hoping it would just be a matter of following the spec!

   

  Thanks

  John

  0

  Comment actions Permalink

Please sign in to leave a comment.