DNP3 Usage Notes / DNP3 Client / DNP3 / Communication Protocols / Speedgoat I/O Blockset

Introduction to DNP3

Distributed Network Protocol 3 (DNP3) is a TCP/IP-based communication protocol and allows interoperability between components in electric grids. These components are either client (DNP3 client) or server (DNP3 server). One DNP3 client connects to multiple DNP3 servers to read and write binary data, analog data and counters. Typical client stations are human machine interfaces (HMI) and supervisory control and data acquisition (SCADA) systems. Typical servers are remote terminal units (RTU) and intelligent electronic devices (IED).

In DNP3 networks, each physical device has a unique IP address. Servers normally listen on TCP port 20000 for incoming connection requests from clients. TCP port numbers on the client side are random. In addition to physical connection, there is a logical layer, namely link layer, where each DNP3 station has a unique DNP3 address. The DNP3 address is an integer number between 0 and 65519. Instead of "DNP3 address", the terms "Client ID" and "Server ID" are used in Speedgoat block masks and documentation. This is for the sake of clarity and to distinguish from "IP address".

Typical Target Machine Configurations

For DNP3 communication with Speedgoat target machines, you can use onboard Ethernet interfaces and plug-in Ethernet I/O modules.

Use the Ethernet Configuration Tool to assign IP addresses to these Ethernet interfaces.

For DNP3, you can use any Ethernet interface whose Configuration is set to IP Protocols.

One real-time target machine can perform multiple DNP3 clients and servers. There are four possible configurations:

One IP Address per Ethernet Interface

One IP address is assigned to one Ethernet interface. This Ethernet interface acts as either one DNP3 client or one DNP3 server in the network. You can install multiple Ethernet I/O modules (providing up to 4 interfaces each) or use additional onboard Ethernet interfaces in order to set up multiple DNP3 clients and servers. As all the Ethernet interfaces of a target machine must be associated with different Ethernet subnets, each DNP3 station must operate in another Ethernet network. If an application requires multiple client stations to communicate with different DNP3 networks, then this target configuration is the correct choice. In contrast, if the simulation of a DNP3 network with multiple servers is required, this setup cannot be used.

Subnet dedication of an Ethernet interface is defined by IP address and subnet mask.

Multiple IP Addresses per Ethernet Interface (IP Aliasing)

IP aliasing can be used to assign multiple IP addresses to a single physical interface. This allows multiple DNP3 clients and servers to be operated on the same Ethernet I/O module or the same onboard Ethernet interface. As the related IP addresses are always associated with the same Ethernet subnet, this configuration is ideal for simulating a DNP3 network containing multiple servers. Even mixed operation (client and server) is possible for the purpose of loopback testing. Alias addresses can be configured in the advanced settings of the Ethernet Configuration Tool or by functions.

Enter the following in the MATLAB command window to manage IP aliasing:

>> ipAliasObj = speedgoat.IpAliasConfiguration()
>> ipAliasObj.add('ETH2', {'192.168.10.31','192.168.10.32','192.168.10.33'})
>> ipAliasObj.remove('ETH2', {'192.168.10.33'})
>> ipAliasObj.add('Host Link', {'192.168.1.15','192.168.1.19'})

Enter the following in the MATLAB command window to check the available Ethernet interfaces and configured IP aliases:

>> ipAliasObj.show()
Interface Name      IP Address          Subnet Mask
---------------     ---------------     ---------------
ETH2                192.168.10.1        255.255.255.0
                    192.168.10.31       255.255.255.255
                    192.168.10.32       255.255.255.255
                    192.168.10.33       255.255.255.255
Host Link           192.168.1.14        255.255.255.0
                    192.168.1.15        255.255.255.255
                    192.168.1.19        255.255.255.255

Multiple TCP Ports per IP Address

This is the normal operation for client stations as each connection of the client to a server requires a separate TCP port. Consequently, you can set up multiple client stations with the same IP address but different TCP ports and different Client IDs. All these client stations would then act in the same subnet.

For testing and simulation, you can even ignore the default server port 20000 and allow multiple servers to listen on different TCP ports. All these servers would then act in the same subnet too.

Multiple DNP3 Nodes per TCP port

According to the DNP3 standard, one TCP port can perform multiple DNP3 nodes on the link layer. The Speedgoat DNP3 blocks do not currently support this type of multi-channel operation.

Runtime License

DNP3 blocks require a runtime license installed on the target machine. Please refer to the Runtime Licensing help.

DNP3 Data Exchange

DNP3 data is mainly exchanged in request-response fashion. The client sends a request frame to the server. The server sends a response frame to the client. The following request types (commands) are supported by the Speedgoat DNP3 blockset:

Read request
Control request
Freeze request
Class assignment
Enable unsolicited messages
Integrity poll

For certain events, the server can send out so-called unsolicited messages. In this case, single read requests are not required.

The header of a DNP3 request contains four essential items of information:

Item	Description
Group	Defines the data area or rather the type of data to which the request refers
Variation	Defines the data type (unsigned integer, float, etc.) and requests additional meta data (timestamp, flags)
Function code	Defines the type of operation (read, write, freeze)
Qualifier code	Addressing mode: all, limited quantity, start-stop index, etc.

The corresponding DNP3 response includes an appropriate response function code, as well as the same values for group and variation as the request.

The DNP3 server manages several data areas (groups). Inputs and outputs are stored in point groups, and data changes are stored as events in event groups. Points and events can be frozen by the client via the freeze command. Frozen point and event values are stored in additional areas (frozen point groups, frozen event groups). The Speedgoat DNP3 blockset for client and server supports the groups below.

Group	Name
01	Binary inputs
02	Binary input events
03	Double-binary inputs
04	Double-binary input events
10	Binary outputs
11	Binary output control
12	Binary output events
13	Binary output control events
20	Counter inputs
21	Frozen counter inputs
22	Counter input events
23	Frozen counter input events
30	Analog inputs
31	Frozen analog inputs
32	Analog input events
33	Frozen analog input events
40	Analog outputs
41	Analog output control
42	Analog output events
43	Analog output control events

Command Overview

Group	Variation	Function Code	Qualifier Codes	Description
01	01*	01		Read binary input
01	02	01		Read binary input with flag
02	01*	01		Read binary input event
02	02	01		Read binary input event with absolute time
02	03	01		Read binary input event with relative time
03	01*	01		Read double-binary input
03	02	01		Read double-binary input with flag
04	01*	01		Read double-binary input event
04	02	01		Read double-binary input event with absolute time
04	03	01		Read double-binary input event with relative time
10	01*	01		Read binary output
10	02	01		Read binary output with flag
11	01*	01		Read binary output event
11	02	01		Read binary output event with time
12	01*	05		Control Relay Output
13	01*	01		Read relay output control event
13	02	01		Read relay output control event with time
20	00*	07		Immediate freeze binary counter
20	00	08		Immediate freeze binary counter (no response)
20	00	09		Freeze and clear binary counter
20	00	10		Freeze and clear binary counter (no response)
20	00	11		Freeze binary counter at time
20	00	12		Freeze binary counter at time (no response)
20	01	01		Read binary counter with flag (32-bit integer)
20	02	01		Read binary counter with flag (16-bit integer)
20	05	01		Read binary counter (32-bit integer)
20	06	01		Read binary counter (16-bit integer)
21	01*	01		Read frozen counter with flag (32-bit integer)
21	02	01		Read frozen counter with flag (16-bit integer)
21	05	01		Read frozen counter with flag and time (32-bit integer)
21	06	01		Read frozen counter with flag and time (16-bit integer)
21	09	01		Read frozen counter (32-bit integer)
21	10	01		Read frozen counter (16-bit integer)
22	01*	01		Read counter event with flag (32-bit integer)
22	02	01		Read counter event with flag (16-bit integer)
22	05	01		Read counter event with flag and time (32-bit integer)
22	06	01		Read counter event with flag and time (16-bit integer)
23	01*	01		Read frozen counter event with flag (32-bit integer)
23	02	01		Read frozen counter event with flag (16-bit integer)
23	05	01		Read frozen counter event with flag and time (32-bit integer)
23	06	01		Read frozen counter event with flag and time (16-bit integer)
30	00	07		Immediate freeze analog input
30	00	08		Immediate freeze analog input (no response)
30	00	09		Freeze and clear analog input
30	00	10		Freeze and clear analog input (no response)
30	00	11		Freeze analog input at time
30	00	12		Freeze analog input at time (no response)
30	01	01		Read analog input with flag (32-bit integer)
30	02	01		Read analog input with flag (16-bit integer)
30	03	01		Read analog input (32-bit integer)
30	04	01		Read analog input (16-bit integer)
30	05	01		Read analog input with flag (32-bit float)
30	06*	01		Read analog input with flag (64-bit float)
31	01	01		Read frozen analog input with flag (32-bit integer)
31	02	01		Read frozen analog input with flag (16-bit integer)
31	03	01		Read frozen analog input with flag and time (32-bit integer)
31	04	01		Read frozen analog input with flag and time (16-bit integer)
31	05	01		Read frozen analog input (32-bit integer)
31	06	01		Read frozen analog input (16-bit integer)
31	07	01		Read frozen analog with flag (32-bit float)
31	08*	01		Read frozen analog with flag (64-bit float)
32	01	01		Read analog input event with flag (32-bit integer)
32	02	01		Read analog input event with flag (16-bit integer)
32	03	01		Read analog input event with flag and time (32-bit integer)
32	04	01		Read analog input event with flag and time (16-bit integer)
32	05	01		Read analog input event with flag (32-bit float)
32	06*	01		Read analog input event with flag (64-bit float)
32	07	01		Read analog input event with flag and time (32-bit float)
32	08	01		Read analog input event with flag and time (64-bit float)
33	01	01		Read frozen analog input event with flag (32-bit integer)
33	02	01		Read frozen analog input event with flag (16-bit integer)
33	03	01		Read frozen analog input event with flag and time (32-bit integer)
33	04	01		Read frozen analog input event with flag and time (16-bit integer)
33	05	01		Read frozen analog input event with flag (32-bit float)
33	06*	01		Read frozen analog input event with flag (64-bit float)
33	07	01		Read frozen analog input event with flag and time (32-bit float)
33	08	01		Read frozen analog input event with flag and time (64-bit float)
40	01	01		Read analog output (32-bit integer)
40	02	01		Read analog output (16-bit integer)
40	03	01		Read analog output (32-bit float)
40	04*	01		Read analog output (64-bit float)
41	01	05		Control analog output (32-bit integer)
41	02	05		Control analog output (16-bit integer)
41	03	05		Control analog output (32-bit float)
41	04*	05		Control analog output (64-bit float)
42	01	01		Read analog output event (32-bit integer)
42	02	01		Read analog output event (16-bit integer)
42	03	01		Read analog output event with time (32-bit integer)
42	04	01		Read analog output event with time (16-bit integer)
42	05	01		Read analog output event (32-bit float)
42	06*	01		Read analog output event (64-bit float)
42	07	01		Read analog output event with time (32-bit float)
42	08	01		Read analog output event with time (64-bit float)
43	01	01		Read analog output control event (32-bit integer)
43	02	01		Read analog output control event (16-bit integer)
43	03	01		Read analog output control event with time (32-bit integer)
43	04	01		Read analog output control event with time (16-bit integer)
43	05	01		Read analog output control event (32-bit float)
43	06*	01		Read analog output control event (64-bit float)
43	07	01		Read analog output control event with time (32-bit float)
43	08	01		Read analog output control event with time (64-bit float)

* Default variation

Documentation

DNP3 Usage Notes

Introduction to DNP3

Typical Target Machine Configurations

Runtime License

DNP3 Data Exchange

Command Overview