DNP3 (Distributed Network Protocol) is an official communication standard for telecontrol technology (see also telecontrol ). The protocol is used as a general transmission protocol between control systems and remote control terminals.
The messages are typically transmitted via serial connections (ITU-T V.24 ( EIA-232 ) / ITU-T V.28 ( EIA-422 )). In order to take current developments into account, DNP3 over LAN / WAN was subsequently defined. This variation of the protocol (the telegrams remained unchanged, only the medium was changed) transmits the messages via the Internet protocol TCP / IP or UDP / IP .
The DNP3 telecontrol protocol is standardized and further developed by the DNP Users Group . The DNP Users Group consists of manufacturers and users of devices with this telecontrol protocol.
Compared to other telecontrol protocols, the existence of acceptance procedures should be emphasized, with the help of which the implementations can be tested or officially certified by the DNP3 Users Group .
The protocol was originally developed and defined by Harris (later GE Harris, now GE Energy ) under the name DNP V3.00 , then passed on to the DNP Users Group in 1993 for further development and maintenance. The original standard is defined in the Basic 4 Documents . However, the DNP Users Group annually publishes technical bulletins with details and further developments of the standard. The status of a DNP3 implementation in a device or a control system is documented by appending the year to the protocol name. So z. B. DNP3-1999 or DNP3-2004 .
Structure of the protocol
- Data Link Layer: Link layer for the secure transmission of telegrams
- Transport Layer: Splitting into and joining of segments into fragments of the application layer
- Application Layer: Receives fragment from the other station, executes it and sends back a response fragment
The DNP3 protocol can be found in many devices from different manufacturers. Well-known manufacturers are:
- Asea Brown Boveri
- GE Energy
- Siemens AG
- Schneider Electric
- Rockwell Automation