DNP3

Application areas 
DNP3 is a telecontrol protocol according to IEEE 1815, and it is used for data exchange in the area of power plants, grid, and other public infrastructure. DNP3 uses Ethernet or serial connections as physical layer.

Product features 
The DNP3 service for the M1 controller is a pure software solution that uses the Ethernet and COM ports on the controller so that no additional hardware is required. Depending on the configuration and license, the service enables the operation of a DNP3 master, a DNP3 outstation or both operating modes at the same time. The set of available services and functions is conform to DNP3 level 2.

Data objects can be generated on the M1 outstation and linked with the process variables of the controller software. To transfer actual values to the master (monitoring direction), there are the possibilities event polling, the polling of static data, the activation of an automatic transfer (unsolicited responses) as well as explicit read accesses. In control direction, the outstation can receive the commands (controls) of the master in order to accept setpoints, commands and parameters. 

When run as a DNP3 master, the M1 can read and write values from standard compliant DNP3 outstation devices. Operation via the user program is as simple here as setting a local digital output. Through the configuration of the master, a logical IO module in accordance with the Unified Fieldbus Model (UFB) can be generated for each outstation. These UFB modules can be operated immediately in the SolutionCenter diagnostic tool or in a visualization. The values in the PLC are made available to the user program in the process image. Alternatively, an event-driven response can also be implemented to new actual values from the outstation. 

Details on supported object groups, variations and function codes of the outstation are provided in the device profile document. In DNP3 there is no corresponding document for the master. However, its features largely correspond to the possibilities of the outstation.

• Complies with Level 2 with some extensions from Level 3 and 4
• Requires for operation on the controller a license file for master, outstation or both simultaneously
• Uses the Ethernet ports and/or serial COM ports of the controller
• Support for unsolicited responses
• Support for time synchronization via DNP3 

• Configuration of data objects via CSV file
• Linking of data objects with existing process variables
• Parallel connection with several masters possible 
  (requires the configuration of several instances)
• Automatic deadband calculation (threshold value filtering) of analog actual values to reduce the data volume
• Time stamp of value changes implicit via the service
• Formation of quality information (flags) implicit via the service, can be set additionally by the application via a quality variable.
• Quality ensured by standardized certification tests

• Access to data objects of the outstation via logical UFB modules
• The currently received values are provided in the process image
• All events with flags and time stamp can be read via the function
• Event-driven handling of received actual values possible