DNP3 Driver

Introduction

The DNP3 protocol is designed to avoid real time data loss even in the event of communication failure. The DNP3 protocol does this by storing point value changes with a timestamp in the Outstation. When communication is lost, the Outstation continues to record events in its event buffer. When communication is restored, the Outstation sends the stored events to Fernhill SCADA. Fernhill SCADA uses the stored events to fill in the data that was missed while the communication link was down.

The Fernhill SCADA DNP3 driver supports these communication options:

Option	Description
Serial	DNP3 over point to point and point to multi-point serial links
TCP/IP	DNP3 over TCP/IP

Fernhill SCADA DNP3 Tags

The DNP3 driver provides these tag types to support communication with DNP3 Outstations:

Tag Type	Version	Description
DNP3 TCP/IP Channel Tag	3.46	An IP Address used for DNP3 TCP/IP communication.
DNP3 Serial Channel Tag	3.46	A serial port used for DNP3 serial communications.
DNP3 Outstation Tag	3.46	A DNP3 Outstation.

To configure Fernhill SCADA to communicate with a DNP3 outstation do the following:

Create and configure one of the following channel tags depending on your communication requirements:
- A DNP3 TCP/IP Channel Tag, or
- A DNP3 Serial Channel Tag.
Create a DNP3 Outstation Tag. Set the Channel property of the DNP3 Outstation Tag to the channel tag you created in step 1.
Create I/O Data Point Tags to represent the points in the DNP3 Outstation. For each I/O Data Point Tag you create:
- Set the IODataSource property to the name of the DNP3 Outstation tag you created in step 2.
- Set the IOItemName property to the point in the DNP3 Outstation.

You can monitor the status of the tags in the Tag Status Window.

Fernhill SCADA I/O Data Point Tags

You can use these I/O Data Point Tags to represent individual data points in the Outstation:

Tag Type	Version	Description
I/O Analog Data Point Tag	3.12	Maps an Analog Data Point Tag to an external data source.
I/O Digital Data Point Tag	3.12	Maps a Digital Data Point Tag to an external data source.
I/O String Data Point Tag	3.12	Maps a String Data Point Tag to an external data source.
I/O Word Data Point Tag	3.12	Maps a 16-bit Word Data Point Tag to an external data source.
I/O Double Word Data Point Tag	3.12	Maps a 32-bit Double Word Data Point Tag to an external data source.
I/O Long Word Data Point Tag	3.48	Maps a 64-bit Long Word Data Point Tag to an external data source.

DNP3 Object Flags and Data Point Tag Quality

DNP3 Outstations send data to the Master Station using DNP3 Objects. A DNP3 Object defines exactly how data should be encoded.

Some DNP3 Objects include Object Flags that provide additional quality indications about the data source. When Fernhill SCADA receives a DNP3 ObjectswithObject Flags, the following logic is used to set data point tag quality:

If the COMM_LOST bit is set, the data point tag quality will be BAD_COMM_FAILURE (24)
Otherwise if the ONLINE bit is not set, the data point tag quality will be BAD_OUT_OF_SERVICE (28)
Otherwise if the RESTART bit is set, the data point tag quality will be BAD_WAITING_FOR_INITIAL_DATA (32)
Otherwise if the object is Analog and the OVER_RANGE bit is set, the data point tag quality will be UNCERTAIN_EGU_EXCEEDED (84)
Otherwise the data point tag quality will be GOOD (192)

When Fernhill SCADA receives a DNP3 ObjectswithoutObject Flags, the data point tag quality will be GOOD (192).

Further Information

DNP3 Point Address Format

To learn how to choose a data location in a DNP3 Outstation.

Serial Communications

For background information on serial communications.

Fernhill SCADA Drivers

For information about other drivers available in Fernhill SCADA.

Glossary

For the meaning of terms used in Fernhill SCADA.