B&B Electronics Command Response Protocol HVD100A3 Uživatelský manuál stáhnout pdf (Strana 18)

14 HDV100A3 Command & Response Manual

B&B Electronics -- 707 Dayton Rd. -- PO Box 1040 -- Ottawa, IL 61350

PH (815) 433-5100 -- FAX (815) 433-5104

To restart reception, send the (01, 02, 01, 11, 00, 15) command to

the HDV.

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:

Byte

Number

Byte Value

(hex)

Byte Function

Start of frame

Number of control bytes

ID bytes 1= J1708

Function code 12 (hex) transmit to J1708 bus

Priority byte 00000010 set bit 0 to 7 see below

Number of data bytes to follow (excludes checksum byte)

Data bytes up to 100 bytes

Checksum

Set the priority bit using the chart below.

Priority Byte Value

Binary Value

Hex Value

00000001

00000010

00000100

00001000

00010000

00100000

01000000

10000000

1 2 ... 13 14 15 16 17 18 19 20 21 22 23 ... 30 31

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B&B Electronics Command Response Protocol HVD100A3 Uživatelský manuál Strana 18