Campbell Hausfeld SDM-CAN - Manual (Page 55)

Appendix C. Application of the
SDM-CAN on Networks Complying with
the J1939 SAE Standards.
This Appendix describes the use of the SDM-CAN in applications where the CAN network
complies to the J1939 standard, which is common in truck, bus and marine applications in the
USA. This appendix is not intended to act as a full reference to those standards, but to simply
describe the coding of the ID parameter and to give examples of how to decode some of the
common, defined J1939 data packets.
C.1 J1939 29-Bit Identifier Format
The J1939 identifier format consists of 6 predefined fields; for a 29-bit identifier
these are:
P - Priority Field (3 bits)
R - Reserved Field (1 bit)
DP - Data Page Field (1 bit)
PF - PDU Format Field (8 bits)
PS - PDU Specific Field (8 bits)
SA - Source Address Field (8 bits)
Table C-1 Mapping of the J1939 Fields into a 29-Bit Identifier
Bi t 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
P
3
P
2 P
1 R
1 D
P P
F
8 P
F
7 P
F
6 P
F
5 P
F
4 P
F
3 P
F
2 P
F
1 P
S
8 P
S
7 P
S
6 P
S
5 P
S
4 P
S
3 P
S
2 P
S
1 S
A
8 S
A
7 S
A
6 S
A
5 S
A
4 S
A
3 S
A
2 S
A
1
C.2 J1939 11-Bit Identifier Format
The J1939 identifier format consists of 2 predefined fields; for an 11-bit identifier
these are:
P - Priority Field (3 bits)
SA - Source Address Field (8 bits)
Table C-2 Mapping of the J1939 Fields into a 11-Bit Identifier
Bit 10 9 8 7 6 5 4 3 2 1 0
P
3
P
2 P
1 S
A
8 S
A
7 S
A
6 S
A
5 S
A
4 S
A
3 S
A
2 S
A
1
Details of identifier field values can be found in the SAE J1939
standard. NOTE
C-1