Reference MVI71-DNPSNET
♦
PLC Platform
Distributed Network Protocol Interface Module
ProSoft Technology, Inc.
Page 77 of 100
September 22, 2008
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.
5.9.1 Design
In order to implement a solution using the module, the PLC 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 Configuration section of this manual. This program will interact with
the module by sending and receiving data and issuing special control commands.
Data tags in the PLC processor contain the data to be used by the module and
the configuration information is stored in the text file, DNPSNET.CFG, stored on
the module's Compact Flash Disk. Before you generate the program or layout the
data files, you must first design your system. Time spent doing system design at
the outset of the project will greatly enhance the success and ease of
development of the project.
Designing the system
System design defines the data requirements of the system, communication
parameters, and module functionality. The application developer should refer to
the person responsible for the DNP master and slave device configurations to
verify that the functionality and data types required for the whole system are
consistent. Review the DNP Device Profile and DNP Subset documentation for a
definition of the level of DNP support offered by the module.
The following topics describe each element of system design.
Data Requirements
This phase of design defines what data elements are to be interfaced in the PLC
processor with the DNP master. The module provides the following data types:
digital input, digital output, counter, analog input and analog output. All
communications between the DNP master and the PLC is through these data
types. Therefore, all data to be used by the system must be contained and
configured in one of these data types.
Summary of Contents for InRax MVI71-DNPSNET
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