DNP3

DNP3 (Distributed Network Protocol, standardized as IEEE 1815) carries SCADA data between a master, the control centre or a SCADA front end, and outstations: the RTUs, IEDs and gateways out in substations, pumping stations and along feeders. An outstation keeps the current value of every point and a buffer of time-stamped events, so a master that polls rarely, or loses its link for an hour, still gets every change in order. Controls go through select-before-operate, so a breaker only moves when the outstation has confirmed exactly which one. DNP3 runs over serial lines, radio, TCP and UDP, and over TLS where the network is not trusted.

Where you meet it

• Distribution and transmission SCADA, above all in North America, Australia and parts of Asia and Africa; IEC 60870-5-104 fills the same role in much of Europe
• Water and wastewater, oil and gas pipelines, and the telemetry of other utilities
• Distributed energy: IEEE 1547-2018 names DNP3 as one of the interfaces of a grid-connected inverter, with IEEE 1815.2 (the MESA profile) mapping its functions

Quickstart

From the command line

Download dnp3ctl from GitHub Releases. No outstation at hand? Start the built-in demo outstation:

dnp3ctl server start

and talk to it from another terminal:

# What does this outstation hold? (integrity poll of link address 10)
dnp3ctl client poll --ip 127.0.0.1 --outstation 10

# Watch events as they arrive, until Ctrl-C
dnp3ctl client monitor --ip 127.0.0.1 --integrity

# Open a breaker with select-before-operate
dnp3ctl client operate --ip 127.0.0.1 --type crob --index 0 --op latch-off

# Synchronize its clock
dnp3ctl client time-sync --ip 127.0.0.1

# Which outstations answer on this subnet?
dnp3ctl discover --subnets 192.168.1.0/24

--url tls://, udp:// and serial:///dev/ttyUSB0 reach the same outstation over other transports, and server start --config serves a simulated RTU from a YAML model of points, controls and files.

From Go

go get github.com/otfabric/go-dnp3

A master that runs an integrity poll and operates a breaker (abridged from the go-dnp3 README):

c, err := client.Dial(ctx, "10.0.0.5:20000",
  client.WithAddresses(1, 10), // master 1, outstation 10
  client.WithReconnect(client.Reconnect{}),
)
if err != nil {
  log.Fatal(err)
}
defer c.Close()

// Events of classes 1 to 3, then every current value.
res, err := c.IntegrityPoll(ctx)
for _, m := range res.Measurements() {
  fmt.Println(m.GV, m.Index, m.Value)
}

// Select-before-operate of breaker 0.
_, err = c.Operate(ctx, client.SelectBeforeOperate, client.CROB(0, app.OpLatchOn, 0, 0))

And an outstation with two points, which produces events as they change:

srv, err := server.New(server.WithAddress(10), server.WithMasters(1), server.WithHandler(breaker))
db := srv.Database()
_ = db.AddBinaryInput(0, server.PointConfig{Class: 1}, app.Binary{Value: true, Flags: app.FlagOnline})
_ = db.AddAnalogInput(0, server.PointConfig{Class: 2, Deadband: 0.5}, app.Analog{Value: 230.1, Flags: app.FlagOnline})
log.Fatal(srv.ListenAndServe(":20000"))

What go-dnp3 and dnp3ctl support