38.4 CAN FD Message Frames
The ISO11898-1:2015 describes the different CAN message frames in detail. Figure 38-7 through Figure 38-12 explain and summarize the construction of the messages and fields.
- CAN Base Frame: Classic CAN 2.0 frame using Standard ID
- CAN FD Base Frame: CAN FD frame using Standard ID
- CAN Extended Frame: Classic CAN 2.0 frame using Extended ID
- CAN FD Extended Frame: CAN FD frame using Extended ID
There are no remote frames in CAN FD frames; therefore, the RTR bit is replaced with the RRS bit (see Figure 38-8). The RRS bit in the CAN FD base frame can be used to extend the SID to 12 bits. When enabled, it is referred to as SID11; it is the Least Significant bit (LSb) of SID[11:0].
Figure 38-9 specifies the control field of the different CAN messages. Before CAN FD was added to the ISO11898-1:2015, the FDF bit was a reserved bit. Now the FDF bit selects between Classic and CAN FD formats.