wilamowski-b-m-irwin-j-d-industrial-communication-systems-2011

DNP3 and IEC 60870-5 58-3
protocol standards for those applications, but will adopt different standards for other applications
(e.g., for safety interfaces such as signaling).
Other major industries with large-scale widely distributed SCADA networks include oil and gas pipeline
monitoring and water and wastewater monitoring. These industries have some requirements in
common with electric power SCADA and some differences.
The oil and gas industries and water and wastewater industries typically have a relatively long time
domain associated with their monitoring requirements: Pressures in gas pipelines and rates of flow and
levels for liquids generally do not change rapidly or need prompt attention. This generally allows for a
slower data collection strategy with a period of data collection in the range from minutes to hours often
being acceptable. One notable exception to this is the prompt reporting of “urgent” alarm conditions
that might necessitate operator intervention or maintenance call out.
For these pipeline industries, there are few additional requirements that are not covered by power system
applications and therefore the electric power protocols and also Modbus (where no time tagging or SOE data
is required) are applicable. Proprietary protocols are also still very common in the oil and gas industries.
In recent years, the water industries in the United Kingdom and Australia have standardized on DNP3 for
SCADA interfaces and are making use of the SOE functionality to allow accurate recording of field actions
while allowing infrequent polling. DNP3 supports an unsolicited reporting mechanism where changes can
be reported from the field without needing a request from the master station. The use of this feature allows
prompt indication of urgent alarm conditions without requiring frequent polling of each remote site.
The IEC 60870 series profiles have not been widely adopted in the oil and gas and water industries,
possibly because of a perception that they are power-system specific.
58.2 Features Common to IEC 60870-5 and DNP3: Data
Typing, Report by Exception, Error Recovery
The International Electrotechnical Commission’s 60870-5 series of standards were developed by the
IEC Technical Committee 57 over the period 1988–2000. Some parts have been updated with subsequent
revisions and extensions. This series includes the IEC 60870-5-101 [1] and 60870-5-104 [2] profiles
for basic telecontrol tasks over serial and TCP/IP links. The IEC 60870-5 series are recognized as the
international standards for electric power SCADA transmission protocols. Their use for that purpose is
mandated in many countries by government legislation and they are widely adopted in Europe and in
countries where European companies and conventions have significant influence.
IEC 60870 parts -5-1 through to -5-5 define a “cookbook” of rules for specifying SCADA Telecontrol
protocols. Part -5-101 (sometimes also known as “Telecontrol 101” or “T101”) specifies a fully defined
profile for basic Telecontrol tasks based on these rules. T101 includes the definition of general-purpose
and power-system-specific data objects and functions directly applicable to the substation to control
center SCADA link. Part -5-104 (“T104”) defines the transmission of T101 over TCP/IP with some
minor functional extensions such as the addition of time tags to control objects.
DNP3 [3] is a general-purpose SCADA protocol based on the design rules in the early parts of IEC
60870 that adds some concepts that are quite different from those defined in later parts of IEC 60870-5.
It defines data types and functions for the transmission of generic SCADA data. While it was designed
for power system application, it does not include power-system-specific data objects.
DNP3 was initially developed by the Canadian SCADA company Westronic and was placed in the public
domain in 1993. It is now maintained by an independent body called the DNP Users Group and is considered
a de facto standard for electric power SCADA communication in North America where it is used by over 80%
of power utilities [4]. DNP3 is also the de facto standard for electric power SCADA communications in most
other English-speaking countries and places where North American vendors have significant market influence.
The creation of DNP3 appears to have been influenced by a pragmatic response to utility market demands for
conformance to the IEC 60870 standard in the years prior to the publication of IEC 60870-5-101. Its placement
© 2011 by Taylor and Francis Group, LLC