B&B Electronics Command Response Protocol HVD100A3 - Manual (Page 13)

HDV100A3 Command & Response Manual-1306cr 9
B&B Electronics -- 707 Dayton Rd. -- PO Box 1040 -- Ottawa, IL 61350
PH (815) 433-5100 -- FAX (815) 433-5104
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
Number
Byte
Value Function
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
Number Byte
Value Function
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.