B&B Electronics HVD100A3 Manual De Usuario
14
HDV100A3 Command & Response Manual-1306cr
B&B Electronics -- 707 Dayton Rd. -- PO Box 1040 -- Ottawa, IL 61350
PH (815) 433-5100 -- FAX (815) 433-5104
Transmitting Data to the J1708 Bus
The HDV100A3 supports standard J1708 commands of up to 21
bytes. Additionally the HDV100A3 can send messages up to 100 bytes to
the J1708 bus. It is the responsibility of the sending software to check for
“ignition off” before using the J1708 bus to send messages with more than
21 bytes to the bus. Failure to check for a “quiet bus” condition before
transmitting a long message may cause erratic bus operation. The format to
send information to the J1708 bus is shown below:
the J1708 bus. It is the responsibility of the sending software to check for
“ignition off” before using the J1708 bus to send messages with more than
21 bytes to the bus. Failure to check for a “quiet bus” condition before
transmitting a long message may cause erratic bus operation. The format to
send information to the J1708 bus is shown below:
Byte
Number
Number
Byte
Value
(hex)
Value
(hex)
Byte Function
1
01
Start of frame
2
03
Number of control bytes
3
01
ID bytes 1= J1708
4
12
Function code 12 (hex) transmit to J1708 bus
5
02
Priority byte 00000010 set bit 0 to 7 see below
6
XX
Number of data bytes to follow (excludes checksum byte)
YY
Data bytes up to 100 bytes
CS
Checksum
Set the priority bit using the chart below.
Priority Byte Value
Binary Value
Hex Value
1 00000001
01
2 00000010
02
3 00000100
04
4 00001000
08
5 00010000
10
6 00100000
20
7 01000000
40
8 10000000
80