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Commands in DNP Slave Protocol |
This Driver supports receiving Select, Operate, or Direct Operate commands for objects 12 Variation 1 and 41 Variations 1, 2, 3, or 4.
If the Command Response Profile option is defined as Wait for Application Response, the full sequence to handle a command is the following:
1.A Select, Operate, or Direct Operate command is received.
2.An individual Tag or Block Tag with parameter N2 or B2 equal to 3 (three), 4 (four), or 5 (five) must be read and handled by the application, such as sending it to another Driver to send it to a device.
3.When receiving an answer of this command to a device, users must write back to the same Tag whose command status was read. If the answer of the command to the device was positive, users must write the same value back. Otherwise, users must write a different value.
4.If no writing is performed to the Tag in an interval of 10 seconds, the Driver sends an answer with status equal to 6, that is, Request Not Accepted. Hardware Problems.
To receive a command request from these objects, users can use an individual Tag or a Block Tag, according to the next objects.
For an individual Tag, the Tag value when read contains the value of the Control Code field. To use the Select and Operate commands, users must create two Tags, each one receiving a reading at the moment the corresponding command occurs, Select or Operate. To use the Direct Operate (5) command, only a single Tag is needed with the following parameters:
•N1: Not used
•N2: 3, 4, or 5
•N3: 1201 or 41XX
•N4: Point index
For a Block Tag, use the previous configurations, but this Block Tag can have up to six Elements. The difference is that, regardless of the command, Select, Operate, or Direct Operate, only a single Block Tag with the next Elements is needed, because the operation is returned in Element 5 (five).
•Element 0: Control Code
•Element 1: Count
•Element 2: On Time
•Element 3: Off Time
•Element 4: Status
•Element 5: Command (3: Select, 4: Operate, or 5: Direct Operate)
For an individual Tag, the Tag value when read contains the value of the Control Code field. To use the Select and Operate command, users must create two Tags, each one receiving the reading at the moment the corresponding command occurs, Select or Operate. To use the Direct Operate (5) command, only a single Tag is needed with the following parameters:
•N1: Not used
•N2: 5
•N3: 1201 or 41XX
•N4: Point index
For a Block Tag, use the previous configurations, but this Block Tag can have up to three Elements:
•Element 0: Value
•Element 1: Status
•Element 2: Command
The next example handles the reception of commands in an Object 12 Variation 1.
// The OpenClose Block Tag contains 5 Elements
// This example assumes sending a received command
// to another DNP Master Driver
Sub OpenClose_OnRead()
Set Digital = Parent.Parent.Item("DigitalReadings")
ControlCode = Item("ControlCode").Value
Trip = 1
Close = 0
CmdOk = 1
Select Case ControlCode
Case 65 'Pulse On Close
VCommand = Close
Case 66 'Pulse off close
VCommand = Close
Case 67 'Latch On Close
VCommand = Close
Case 68 'Latch Off Close
VCommand = Close
Case 129 'Pulse On Trip
VCommand = Trip
Case 130 'Pulse Off Trip
VCommand = Trip
Case 131 'Latch On Trip
VCommand = Trip
Case 132 'Latch Off Trip
VCommand = Trip
Case Else 'Invalid command
CmdOk = 0
End Select
If Not(CmdOk) Then
WStatus = 7
Else
If Digital.Item("STATUSDL01").WriteEx(VCommand, , , WStatus) Then
WStatus = 0 'Forces value 0 - Success
'Status expected by the Master in case of error
'Select Case WStatus
' Case 1
' Endtext = "Operate received after a selection time-out"
' Case 2
' Endtext = "No message of previous selection"
' Case 3
' Endtext = "Format error in the command"
' Case 4
' Endtext = "Operation not supported for this point"
' Case 5
' Endtext = "Queue is full or point is already active"
' Case 6
' Endtext = "Hardware problem"
' Case Else
' Endtext = "Undefined problem"
'End Select
Else
WStatus = 7
End If
End If
Item("Status").Value = WStatus
Write(EWriteSyncMode)
End Sub