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.
As opposed to open standards in the "telecom" world like SNMP, DNP3 is commonly used in process-control environments. These can include water, wastewater, and manufacturing. As with any protocol, the key is to maintain compatibility within your system.
DNP3 uses a Master/Remote Model
A typical DNP3 master/remote
monitoring system architecture.
DNP3 is typically used between centrally located masters and distributed remotes. The master (think Operating Center) provides the interface between the human network manager and the monitoring system. The remote (think sub-station) 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.