ProSoft Technology MVI69-DNP - Manual (Page 87)

Reference MVI69-DNP ♦ CompactLogix or MicroLogix Platform
DNP 3.0 Master/Slave Communication Module
ProSoft Technology, Inc. Page 87 of 129
November 3, 2008
5.2.4 Data Flow between MVI69-DNP Module and CompactLogix
Processor
The following topics describe the flow of data between the two pieces of
hardware (CompactLogix processor and MVI69-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 is dependent on this configuration.
The following topics discuss the operation of these drivers.
Slave Driver
The Slave Driver mode allows the MVI69-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 slave port driver receives the configuration information from the configuration 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 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.