Detailed Description of General Function Codes
Command Acknowledgement
All commands sent to the device will be acknowledged. If no error occurs an ACK will be sent with the ID byte that accompanied the command. If an error occurred, a NACK will be sent with the ID byte that accompanied the command as well as a Function code of $05 and the Error Code. The responses will not be shown for each command since it is the same for almost all commands. Below is the format of the ACK/NACK response. If an ACK/NACK response is different for a particular command, it will be specified.
ACK/NACK Format:
Byte | Byte | Function |
Number | Value |
|
1 | 01 | Start of frame |
2 | 01 or 03 | Number of control bytes = 1 for ACK, 3 for NACK |
3 | aa | ID byte 08 = internal command |
4 | bb | Function code 02 = send time stamp |
5 | cc |
|
6 | 00 | Number data bytes |
7 | CS | Checksum |
aa – ID Byte
$01 = J1708 Interface
$02 = J1939 Interface $05 = Device Id
$08 =
$09 = Message Xmit OK Response bb – FC Byte
None = Command Received and Valid $05 = A error was detected, NACK
cc – CD Byte
None = No Error Condition Error Code = See Section 5.10
4 | HDV100A3 Command & Response | |
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