B&B Electronics HVD100A3 Detailed Description of General Function Codes, Command Acknowledgement

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 = RS-232 Interface

$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 Manual-1306cr
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