B&B Electronics 1939STB manual SAE-J1939 Control Header, J1939 Message Frame

SAE-J1939 Control Header

Bytes 7 though 10 are the bytes that set the header information (“Arbitration Field” in the following table) for the SAE-J1939 bus. The areas shown in Table 27 in dark gray are set by the CAN specification and are NOT modified by SAE-J1939.

Table 27. J1939 Message Frame

ARBITRATION FIELD

CONTROL

DATA

CRC

ACK

EOF

S

Identifier

S

I

Identifier

R

R

R

D

O

(11 Bits)

R

D

Extension

T

1

0

L

F

S

E

(18 Bits)

R

C

1

11 Bits

1

1

18 Bits

1

6 Bits

64 Bits

16 Bits

2 Bits

7 Bits

The frame above shows the entire J1939/CAN frame.

Table 28 on the following page shows the Arbitration field in detail. Dark gray areas are part of the CAN standard and are set by the controller. The double black lines separate the CAN message identifiers (upper part) from the SAE-J1939 message identifiers (lower part). The area between the black lines highlighted in dark gray/white letters shows the bytes that must be entered to set up the SAE-J1939 message header. In the back of the manual you will find a worksheet, (Appendix A) and an example (Appendix B) to help set up the message header.

1939STB4600 Manual 19

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