DNP3 Master/ DNP3 Net Client

Predefined Master Command

The predefined master command of the DNP3 master contains these fields:

Command	Status	Meaning
Read_Class	Yes	read class command
Read_Group	Yes	read group command
Freeze_Counter	Yes	freeze counter command
Unsolicited_Class	Yes	class unsolicited command
Time_Sync	Yes	time synchronization command
Restart	Yes	restart command

Command Implementation Method

Commands can be mapped to the CPU memory, either:

32-bit CPU register (command and status) through %MW. Both the command and status are 16 bits.
64-bit CPU register (command and status) through %MW. Both command and status are 32 bits.

Commands are implemented each time when the value in the configured CPU memory changes. This allows the user to control easily the command implementation by changing the value in the CPU memory.

NOTE: In DNP3 master/client, the binary output is triggered to send out on the change of low byte of CPU mapping (%MW) since firmware V1.6 (instead of a change of last bit of CPU mapping (%MW) in previous firmware versions).

Command Status Register

Certain commands have a status register that lets the user know if the command was successfully executed. The status register is a 16-bit word. For example, if a command is mapped to CPU register %MW1, the corresponding status register is automatically mapped to %MW2.

NOTE: When a command is mapped to a register and the command has a command status, the status register is automatically mapped to the following register.

If a command has a result, the low byte of the status register increments automatically to indicate that the status is for the command. The high byte is the status of the command.

NOTE: If the high byte of command status has a result 0, this means that it has completed successfully.

A DNP3 command status register contains these fields:

Status value	Description
0	The command has completed successfully.
1	A response was received but the requested command is not yet complete.
2	The command did not transmit as expected.
3	The command has timed out.
4	The command has been canceled.
5	The response to a select or an execute did not echo the request.
6	The command did not execute.
7	The response to a command had IIN bits set indicating that the command was not executed.