DNP3

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DNP3 (Distributed Network Protocol) is a set of communications protocols used between components in process automation systems. Its main use is in utilities such as electric and water companies. Usage in other industries is not common, although technically possible. Specifically, it was developed to facilitate communications between various types of data acquisition and control equipment. It plays a crucial role in SCADA systems, where it is used by SCADA Master Stations (aka Control Centers), Remote Terminal Units (RTUs), and Intelligent Electronic Devices (IEDs). It is used only for communications between a master station and RTUs or IEDs. ICCP, the Inter-Control Centre Protocol, is used for inter-master station communications.

1 History
2 Technical details
3 See also
4 External links

[edit] History

While IEC 60870-5 was still under development and had not been standardized, there was a need to create a standard that would allow interoperability between various vendors' SCADA components for the electrical grid. Thus, in 1993, GE-Harris Canada (formerly known as Westronic, Inc.) used the partially completed IEC 60870-5 protocol specifications as the basis for an open and immediately implementable protocol that specifically catered to North American requirements. The protocol is designed to allow reliable communications in the adverse environments that electric utility automation systems are subjected to, being specifically designed to overcome distortion induced by EMI, aging components (their expected lifetimes may stretch into decades), and poor transmission media.

Although the protocol was designed to be reliable, it was not designed to be secure from attacks by hackers and other malevolent forces that could potentially wish to disrupt control systems to disable critical infrastructure. Thus, much work is currently being done to provide security for the systems that use the DNP3 protocol.

The DNP3 protocol is also referenced in IEEE Std. 1379-2000, which recommends a set of best practices for implementing modern SCADA Master-RTU/IED communication links.

[edit] Technical details

DNP3 is, in standard networking terms, a layer 2 protocol. It provides multiplexing, data fragmentation, error checking, link control, prioritization, and layer 2 addressing services for user data.

It makes particularly heavy use of Cyclic Redundancy Checks (CRCs) embedded in its data packets, in an attempt to deal with the very noisy environments in which it is typically used.

Many modern applications can now carry DNP3 messages over TCP/IP..