The development of the distributed network protocol (DNP)
was a comprehensive effort to achieve open, standards-based interoperability
between substation computers, RTUs, IEDs, and master stations (except
intermaster station communications) for the electric utility industry. DNP is
based on the standards of the IEC TC 57, WG 03.
DNP has been designed to be as close to compliant as
possible to the standards as they existed at time of development with the
addition of functionality not identified in Europe but needed for current and
future North American applications (e.g., limited transport-layer functions to
support 2K block transfers for IEDs as well as radio frequency [RF] and fiber
support).
The present version of DNP is DNP3, which is defined in
three distinct levels. Level 1 has the least functionality (for simple IEDs),
and Level 3 has the most functionality (for SCADA master station communication
frontend processors).
The short-term benefits of using DNP are interoperability
between multi-supplier devices; fewer protocols to support in the field;
reduced software costs; no protocol translators needed; shorter delivery
schedules; less testing, maintenance, and training; improved documentation;
independent conformance testing; and support by independent user group and
third-party sources (e.g., test sets, source code).
In the long-term, further benefits can be derived from using
DNP, including easy system expansion; long product life; more value-added
products from suppliers; faster adoption of new technology; and major
operations savings
DNP was developed by Harris, Distributed Automation
Products, in Calgary, Alberta, Canada. In November 1993 responsibility for
defining further DNP specifications and ownership of the DNP specifications was
turned over to the DNP User Group, a group composed of utilities and suppliers
who are utilizing the protocol.
The DNP User Group is a forum of over 300 users and
implementers of the DNP3 protocol worldwide. The major objectives of the user
group are to maintain control of the protocol and determine the direction in
which the protocol will migrate; to review and add new features, functions, and
enhancements to the protocol; to encourage suppliers and utilities to adopt the
DNP3 protocol as a standard; to define recommended protocol subsets; to develop
test procedures and verification programs; and to support implementer
interaction and information exchange.
The DNP User Group has an annual general meeting in North
America, usually in conjunction with the DistribuTECH Conference in
January/February. The web site for DNP and the DNP User Group is www.dnp.org.
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