B&B Electronics HVD100A3 manual Byte Function Number Value, Reply from HDV100A3

Time Stamp Information

The HDV100A3 supports a four-byte rolling time stamp with a resolution of 1.5 microseconds per bit. The maximum time stamp value is 6,442.45 seconds before roll over. The 4-byte time stamp will be added to all transmission from the bus. The time stamp will be added to the transmission confirmation message.

The host application can request that the HDV100A3 send a time stamp, formatted as follows.

Byte	Byte	Function
Number	Value
1	01	Start of frame
2	02	Number of control bytes
3	08	ID byte 08 = internal command
4	02	Function code 02 = send time stamp
5	00	Number data bytes
6	0D	Checksum
Reply from HDV100A3
Byte	Byte	Function
Number	Value
1	01	Start of frame
2	05	Number of control bytes
3	0A	ID 0A = time stamp
4	XX	Time msb
5	XX	Time msb-1
6	XX	Time msb – 2
7	XX	Time lsb
8	00	Data bytes 00
9	CS	Checksum

The time stamp is attached to all messages received from the vehicle bus as part of the control header. After the start of frame byte, the number of control bytes, ID byte and the next 4 bytes are the time stamp. The fourth byte is the MSB the seventh byte is the LSB.

Message time stamping is the default condition when the HDV100A3 is placed in the smart mode. To stop the time stamp from being added to the J1708 message, send the following command to the HDV100A3.

HDV100A3 Command & Response Manual-1306cr 9

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