Campbell Scientific SDM-CAN Datalogger to CANbus Interface - Manual (Page 57)

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
C-1