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1. Introduction
PXM 4/6/8K DNP3 Ethernet Communications User Manual
MN150005EN January 2017 www.eaton.com
1. Introduction
This document contains the Power Xpert
®
Meter (PXM
Meter) 4000/6000/8000 Series device Distributed Network
Protocol (DNP) 3 ethernet communication Level-2 device
profile along with a detailed explanation of the web utility to
configure DNP3 parameters of the PXM Meter.
otee:
N
The PXM 4/6/8K supports DNP3 ethernet communi-
cation. DNP3 serial communication is not supported.
2. DNP3 Protocol Primer
Acknowledgment:
Base materials used in Section 2 of this
manual were provided by and used with the permission of
the DNP Users Group www.dnp.org.
This is a primer for Users who want a quick understand-
ing of DNP3 without having to comb through the tedious
details of a complex specification. The writing style is
meant to be informal and personal.
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Let us start with what it is. Protocols define the rules by
which devices talk with each other, and DNP3 is a protocol
for transmission of data from point A to point B using serial
and IP communications. It has been used primarily by utili-
ties such as the electric and water companies, but it func-
tions well for other areas.
A typical electric company may have a common operations
center that monitors all of the equipment at each of its
substations. In the operations center, a powerful computer
stores all of the incoming data and displays the system for
the human operators. Substations have many devices that
need monitoring (Are circuit breakers opened or closed?),
current sensors (How many amperes are flowing?) and
voltage transducers (What is the line potential?). That only
scratches the surface. A utility is interested in monitor-
ing many parameters, too numerous to discuss here. The
operations personnel often need to switch sections of the
power grid into or out of service. Computers are situated
in substations to collect the data for transmission to the
master station in the operations center. The substation
computers are also called upon to energize or de-energize
the breakers and voltage regulators.
DNP3 uses the term
outstation
to denote remote comput-
ers as are found in the field. The term
master
is used for
the computers in the control centers.
DNP3 provides the rules for remotely located computers
and master station computers to communicate data and
control commands. DNP3 is a non-proprietary protocol that
is available to anyone by visiting the web site www.dnp.
org. Only a nominal fee is charged for documentation, but
otherwise it is available worldwide with no restrictions. This
means a utility can purchase master station and outsta-
tion computing equipment from any manufacturer and be
assured that they will reliably talk to each other. Vendors
compete based upon their computing equipment’s features,
costs and quality factors instead of who has the best pro-
tocol. Utilities are not bound to one manufacturer after the
initial sale.
What do the computers talk about? Outstation computers
gather data for transmission to the master.
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●
Binary input data that is useful to monitor two-state
devices. For example, a circuit breaker is closed or
tripped; a pipeline pressure alarm shows normal or exces-
sive.
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●
Analog input data that conveys voltages, currents, power,
reservoir water levels, and temperatures.
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●
Count input data that reports energy in kilowatt hours or
fluid volume.
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Files that contain configuration data.
The master station issues control commands that take the
form of:
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Close or trip a circuit breaker, start or stop a motor, and
open or close a valve; and/or
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Analog output values to set a regulated pressure or a
desired voltage level.
Other things the computers talk to each other about are
synchronizing the time and date, sending historical or
logged data, waveform data, and on and on.
2.1 Why DNP3?
DNP3 was designed to optimize the transmission of data
acquisition information and control commands from one
computer to another. It is not a general purpose protocol
like those found on the Internet for transmitting email,
hypertext documents, SQL queries, multimedia, and huge
files. It is intended for Supervisory Control and Data
Acquisition (SCADA) applications.
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Readers should not assume this document contains formal rules, which are only provided by the DNP3 Specification volumes.
