User manual

IEC61131 User and Reference Manual
April 22, 2008
446
DNP3 User and Reference Manual
The manual details implementation of the Distributed Network Protocol (DNP3) driver on
SCADAPack controllers. While we continuously improve upon the contents of this manual to
simply the driver configuration tasks, we also assume that users attempting to configure the DNP
protocol on a SCADAPack controller have some preliminary understanding of the DNP3
communication protocol.
DNP3 Protocol Overview
DNP, the Distributed Network Protocol, is a standards-based communications protocol developed to
achieve interoperability among systems in the electric utility, oil & gas, water/waste water and
security industries. This robust, flexible non-proprietary protocol is based on existing open standards
to work within a variety of networks.
DNP offers flexibility and functionality that go far beyond conventional communications protocols.
Among its robust and flexible features DNP 3.0 includes:
 Multiple data types (Data Objects) may be included in both request and response messages.
 Multiple master stations are supported for outstations.
 Unsolicited responses
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may be initiated from outstations to master stations.
 Data types (Objects) may be assigned priorities (Class) and be requested based on the priority.
 Addressing for over 65,000 devices on a single link.
 Time synchronization and time-stamped events.
 Broadcast messages.
 Data link and application layer confirmation
 Internal indications that report the health of a device and results of last request.
 Select-Before-Operate which is the ability to choose extra reliability when operating outputs.
DNP Architecture
DNP is a layered protocol that is based on the Open System Connection (OSI) 7-layer protocol. DNP
supports the physical, data link and application layers only and terms this the Enhanced Performance
Architecture (EPA). In addition to these three layers an additional layer, the pseudo-transport layer,
is added to allow for larger application layer messages to be broken down into smaller frames for the
data link layer to transmit.
Object Library The data objects (Binary Inputs, Binary Outputs, and Analog Inputs
etc.) that reside in the master or outstation.
Application Layer Application tasks for sending of solicited requests (master
messages) to outstations or sending of unsolicited responses from
outstations. These request and response messages are referred to as
fragments in DNP.
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Unsolicited responses are also known as unsolicited messages