DNP3 is a communications protocol used in SCADA and remote monitoring systems. It is widely used because it is an open protocol, meaning any manufacturer can develop DNP3 equipment that is compatible with other DNP3 equipment.
Since its introduction in 1993 as an immediately deployable solution for monitoring critical infrastructure status and allowing reliable remote control, Distributed Network Protocol (DNP or DNP3) has achieved widespread acceptance. GE-Harris Canada (formerly Westronic, Inc.) is generally credited with the seminal work on the protocol, but it is now implemented by an extensive range of manufacturers in a variety of industrial applications.
DNP3 is based on an object model that greatly reduces the bit mapping of data that is traditionally required by other less object oriented protocols. It also reduces the wide disparity of status monitoring and control paradigms generally found in protocols that provide virtually no pre-defined objects. Purists of these alternate protocols would insist that any required object can be 'built' from existing objects. Having some pre-defined objects though, makes DNP3 a somewhat more comfortable design and deployment framework for SCADA engineers and technicians.
A typical DNP3 master/remote monitoring system architecture.
DNP3 is typically used between centrally located masters and distributed remotes. The master provides the interface between the human network manager and the monitoring system. The remote provides the interface between the master and the physical device(s) being monitored and/or controlled. The master and remote both use a library of common objects to exchange information. The DNP3 protocol contains carefully designed capabilities that enable it to be used reliably even over media that may be subject to noisy interference.