Preview of DNP3

The chapter provides an overview of Distributed Network Protocol Version 3.3 (DNP3). DNP3 is a telecommunications standard that defines communications among master stations, remote telemetry units, and other intelligent electronic devices. A key feature of the DNP3 protocol is that it is an open protocol standard and is adopted by a significant number of equipment manufacturers. DNP3 supports multiple-slave, peer-to-peer, and multiple-master communications. It supports the operational modes of polled and quiescent operation. In the case of DNP3 devices with a network port, DNP3 is encapsulated within Transmission Control Protocol/Internet Protocol Ethernet packets. Although this does add the overhead associated with these packets, it provides an effective means of using local or wide area networks to cater to supervisory control and data acquisition communications. DNP3 is recognized as having a strong compliance system. Apart from a comprehensive specification of data objects, DNP3 has a detailed compliance certification system. This is based on having defined implementation sub-sets to which devices must be certified. This provides a means to manufacturers to implement reduced function systems that still provide defined levels of functionality.