B&B Electronics HVD100A3 manual J1708 Commands, Receiving Data from the J1708 Bus

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J1708 Commands

Receiving Data from the J1708 Bus

After the HDV100A3 is set into its Intelligent mode of operation and the RS-232 data rate is configured, you are now ready to communicate with the J1708 bus. A receive command must be sent to the HDV100A3 before attempting to transmit to the bus. The receive message synchronizes the HDV100A3 with the bus. To start receiving J1708 bus data, send the following to the HDV100A3.

Byte

Byte Value

Byte Function

Number

(hex)

 

1

01

Start of frame

2

02

The number of control bytes

3

01

ID byte 01= J1708

4

11

Function code 11 hex start receive

5

00

Number of data bytes (00 place holder)

6

15

Checksum (bytes 1 through 5 added together)

After sending this command to the device, the device will respond with a confirmation message. The message confirms that the command was received by the HDV100A3 and the checksum verified correctly. The reply from the device is formatted as follows:

Byte

Byte Value

Byte Function

Number

(hex)

 

1

01

Start of frame byte

2

01

Control byte

3

01

ID byte (ID of the sent message)

4

00

Number of data bytes

5

03

Checksum

The confirmation message is sent in response to a command sent to the device. The ID byte and the check-sum will change with different commands but the format will remain the same. If the checksum is not correct an error message is sent. Its format is covered at the end of this document.

To stop receiving data from the J1708 bus send the following command to the HDV100A3.

12

HDV100A3 Command & Response Manual-1306cr

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PH (815) 433-5100 --

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Contents HDV100A3 Command Response Protocol Page Table of Contents Do Not Transmit Any Messages to the network Intelligent Mode Verification IntroductionIntelligent Mode Command Protocol Intelligent Mode Message StructureSOF Control Field StructureFormatting the Control Bytes Command Acknowledgement Detailed Description of General Function CodesRS-232 Baud Rate Setup HDV100A3 Command & Response Manual-1306cr Setting Baud 1, Baud Baud Rate Setup Table Byte Byte Function Number Value Hex Baud Rate ExampleUB3 Byte Function Number Value Reply from HDV100A3Function code 20 = stop time stamping Master Reset Command Vendor InformationReceiving Data from the J1708 Bus J1708 CommandsByte Byte Value Byte Function Number Hex Function code 10 hex stop receive Transmitting Data to the J1708 Bus Priority Byte Value Binary Value Hex ValueID bytes 9 = transmit OK Set Filter Active Byte Function Number Value J1708 Message FilterSet Filter Off Byte Function Number Value Broadcast Message DataByte 4 Values Byte 6 Priority ValuesJ1939 Commands Start Receive on J1939 Bus Stop Receive on J1939 BusArbitration Field Y1, Y2, Y3, Y4 Message received from the HDV will be formatted as follows Transmit Data to J1939 Bus MSB-1MSB-2 Set MaskSet Filter 1 to HDV100A3 Command & Response Manual-1306cr J1939 Header Worksheet Error Codes DEC HEX