Diagnostic with SAE J1939 - Usage of CDD and DBC
The SAE J1939 recommended practice contains several Diagnostic specific frames with DMx as acronym.
Some of these frames are used for diagnostic purposes „on-board“, during the drive. They build for instance the input for the central display, informing the driver on actual defects. Most of these DM-frames are broadcasted (BAM). They are defined in the J1939 dbc.
As Off-Board diagnostic is concerned, and for the communication with an external workshop terminal, especially in Europe KWP2000 or UDS is used. Both Diagnostic protocols require ISO TP 15765 as transport protocol. To avoid collision with J1939, special care has been taken within ISO TP 15765-2 (Annex A) concerning the TP-specific 29 bits long frames definition.
In particular the value 0 is given to both Extended Data Page (EDP=0) and Data Page (DP=0) bit fields in the 29 bits Identifier.
As a consequence, only 4 TP-specific identifiers are possible for Diagnostics purposes, if J1939 is used. These identifiers shall be defined in the CDD of CANoe's Diagnostics configuration:
For normal fixed addressing:
- 0x18DA + DA + SA, for physical addressing
- 0x18DB + DA + SA, for functional addressing
For mixed addressing:
- 0x18CE + DA + SA for physical addressing
- 0x18CD + DA + SA for functional addressing
If you have a CDDT file with an extended CAN address interface it is possible to copy this interface to the other CDDT with a CANdelaStudio Admin Edition. If you need a sample CDDT, please contact Vector Support.