B&B Electronics LDVDSV2-S-P9D - Manual - Manual (Page 5)

OBDII Streamer Command & Response
V2.11
Page 5/49
Communication Protocol Definition
All commands and responses to or from the OBDII Streamer are formatted in this style.
Byte Byte Byte(s) Byte Byte(s) Byte
Start of Frame Control Length Control Bytes Data Length Data Bytes Checksum
Start of Frame
0x01 – always 0x01.
Control Length
The number of control bytes in the current message. The control
length of a request or response varies by command and will be
defined under each command’s heading in this document.
Control Byte(s)
The first control byte in a request is the command being sent. In a
response the control byte will be 0x80 greater than the request
control byte.
Each command or response may have additional control bytes as
defined by the specific command or response. Each message must
have at least one control byte.
Data Length
The number of data bytes in the current message. Zero data byte
messages are valid.
Data Bytes
This field contains the data portion of the message.
Checksum
The checksum is a one-byte sum of all bytes including Start of
Frame, Control Length, Control Bytes, Data Length, and Data
Bytes.
Checksum = Sum AND 0xFF