EtherNet/IP

EtherNet/IP carries the Common Industrial Protocol (CIP) over standard Ethernet, TCP and UDP. A scanner, usually a PLC, opens connections to adapters: I/O blocks, drives, valve manifolds, robots, scales and sensors. It then exchanges their assembly data cyclically over UDP at a requested packet interval, from tens of milliseconds down to one. Next to that cyclic implicit traffic, any device can be asked about itself and configured with explicit request and response messages that read and write the attributes of its objects. ODVA maintains the specification, and the same CIP application layer also runs over DeviceNet and ControlNet.

Where you meet it

• Factory and process automation, above all with Rockwell Automation ControlLogix and CompactLogix controllers, and with Omron, Schneider Electric, Keyence and many other vendors
• Drives, I/O, valve islands and robots on machines and packaging lines, often next to Modbus TCP and PROFINET on the same plant floor
• Data collection, historians and edge gateways that read controller tags or watch device health without a programming tool
• Energy and infrastructure sites run by the same controllers, such as battery storage, water treatment and building plant

Quickstart

From the command line

Download ethernetipctl from GitHub Releases. No device at hand? Start the simulated adapter, with an emulated Logix tag database:

ethernetipctl adapter --listen 127.0.0.1 --echo --logix

and talk to it from another terminal:

# Which devices answer on this segment? (one ListIdentity broadcast)
ethernetipctl discover --address 255.255.255.255

# Who is it, and is it healthy?
ethernetipctl identify 127.0.0.1
ethernetipctl diagnose 127.0.0.1

# Read the product name, decoded
ethernetipctl read 127.0.0.1 @1/1/7 --type SHORT_STRING

# Watch input assembly 100 through an input-only I/O connection
ethernetipctl io 127.0.0.1 --config 151 --output 152 --input 100 --input-size 32 --rpi 50ms

# A Logix tag, as JSON for a script
ethernetipctl tag read 127.0.0.1 Count --format json

--route 1/0 reaches a controller behind its communication module through the backplane, --connected sends requests over a Class 3 connection, and adapter --config serves a device from a YAML model of identity, assemblies and tags. Commands that change a device need --yes.

From Go

go get github.com/otfabric/go-ethernetip

A client that reads the identity and an attribute, then a scanner that opens a Class 1 I/O connection (abridged from the go-ethernetip README):

c, err := client.Dial(ctx, "192.168.1.10") // TCP 44818
if err != nil {
  log.Fatal(err)
}
defer c.Close()

id, err := c.Identity(ctx) // Get_Attributes_All of the Identity object
name, err := c.GetAttributeSingle(ctx, cip.ClassIdentity, 1, 7)

s, err := scanner.New(c) // UDP 2222
io, err := s.Open(ctx, scanner.IOConfig{
  ConfigInstance: 151, OutputInstance: 150, InputInstance: 100,
  OutputSize: 32, InputSize: 32, RPI: 10 * time.Millisecond,
  Reconnect: &scanner.Reconnect{},
})
_ = io.SetOutput(out)     // sent from the next interval on
in, run, at := io.Input() // the last input and when it arrived

And an adapter with three assemblies that a PLC can connect to:

srv, err := server.New(server.WithIdentity(cip.Identity{
  VendorID: 0xFFFF, DeviceType: cip.DeviceTypeCommunicationsAdapter,
  ProductCode: 1, Revision: cip.Revision{Major: 1, Minor: 0},
  SerialNumber: 42, ProductName: "My adapter",
}))
in, _ := srv.AddAssembly(100, server.AssemblyInput, 32)
out, _ := srv.AddAssembly(150, server.AssemblyOutput, 32)
_, _ = srv.AddAssembly(151, server.AssemblyConfig, 10)
out.OnWrite(func(data []byte, run bool) { /* drive the outputs */ })
_ = in.SetData(inputs)
log.Fatal(srv.ListenAndServe(":44818"))

What go-ethernetip and ethernetipctl support