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Reference MVI56-DNP
♦
ControlLogix Platform
User Manual
DNP 3.0 Server
Page 104 of 171
ProSoft Technology, Inc.
July 21, 2011
Data Flow Between MVI56-DNP Module and ControlLogix Processor
The following topics describe the flow of data between the two pieces of
hardware (ControlLogix processor and MVI56-DNP module) and other nodes on
the DNP network under the module’s different operating modes. Each port on the
module is configured to emulate a DNP Master device or a DNP slave device.
The operation of each port depends on this configuration. The following topics
discuss the operation of each mode.
Slave Driver
The Slave Driver Mode allows the MVI56-DNP module to respond to data read
and write commands issued by a Master on the DNP network. The following flow
chart and associated table describe the flow of data into and out of the module.
Step Description
1
The DNP slave port driver receives the configuration information from the DNP.CFG file.
This information configures the serial port and define the slave node characteristics.
Additionally, the configuration information contains data that can be used to offset data in
the database to addresses requested in messages received from Master units.
2
A Host device (DNP Master unit) issues a read or write command to the module’s node
address. The port driver qualifies the message before accepting it into the module.
3
After the module accepts the command, the data is immediately transferred to or from
the appropriate internal database in the module. If the command is a read command, the
data is read out of the database and a response message is built. If the command is a
write command, the data is written directly into the database and a response message is
built.
4
After the data processing has been completed in Step 3, the response is issued to the
originating Master node.
5
Counters are available in the Status Block that permit the ladder logic program to
determine the level of activity of the Slave Driver.