ProSoft Technology MVI69-DNPSNET - Manual (Page 79)

Reference MVI69-DNPSNET ♦ CompactLogix or MicroLogix Platform
Distributed Network Protocol Interface Module
ProSoft Technology, Inc. Page 79 of 119
November 3, 2008
Step Description
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.
6 The module constantly monitors for command control blocks from the processor. If a
valid block is received, the function is executed. Additionally, data is constantly being
exchanged between the module and the processor.
Review the Module Configuration section for a complete list of the parameters
that must be defined for a slave port.
5.3 MVI69-DNPSNET Application Design
This documentation describes the MVI69-DNPSNET module configuration and
setup as it applies to application design. Before attempting to implement this
module with a DNP network, verify that the whole design of the system is
complete. This includes definition of all the data types and point counts required
for each type, all communication parameters required for the network including
media type and the use of advanced features such as unsolicited messaging.
These must be defined for all master and slave devices on the network.
Additionally, the DNP Device Profiles and DNP Subset Definition documents for
each device must be reviewed to make sure all the devices will interact on the
network as expected. Failure to fully understand these important documents for
all devices on the network will usually lead to many problems when implementing
the design.
It is important to fully understand the DNP specification as outlined in the Basic
Four Documents. These are available to users of the DNP users group. It is
recommended that all users of the module have access to these important
documents as they define the DNP data types, functions and variations. It will be
very difficult to implement the module without an understanding of the protocol
and the rules that are defined in the specification. Additionally, potential users
should review the DNP Subset and Conformance Test documents and the
document that discusses DNP protocol support on Ethernet using the UDP and
TCP protocols. These documents provide auxiliary information on the protocol.
All of these documents are available to members of the DNP User Group at
http://www.dnp.org (http://www.dnp.org). Please check this site for other
important information regarding the DNP protocol.
In order to implement a solution using the module, the CompactLogix or
MicroLogix processor must be set up using predefined user data structures. The
data transfer interface requires ladder logic in order to interface data in the
module with that in the processor. The program required for data transfer is
developed in ladder and is discussed in the Module Set Up section. This
program will interact with the module by sending and receiving data and issuing
special control commands.