PROFINET

PROFINET IO is the industrial Ethernet that PROFIBUS & PROFINET International (PI) maintains and that Siemens and many other automation vendors build on. An IO-Controller, usually a PLC, owns a set of IO-Devices: remote I/O stations, drives, valve terminals, robots, sensors and gateways. It finds each one by its station name with DCP, establishes an application relationship (AR) with the configuration it expects, writes the parameters, and then exchanges the process data in cyclic real-time frames directly on Ethernet, every few milliseconds, with a status byte next to every value. Alarms, diagnosis and records travel next to the cyclic data, and a GSDML file describes each device to the engineering tool.

Where you meet it

• Factory and process automation with Siemens SIMATIC controllers and the many PLCs, drives and I/O systems that speak PROFINET, often next to EtherNet/IP and Modbus TCP in the same plant
• Machine building, packaging, automotive and logistics lines, where commissioning means naming devices, assigning addresses and checking the cabling
• Ring networks with media redundancy (MRP), so that one broken cable does not stop a line
• Energy and infrastructure sites run by the same controllers: battery storage, water treatment, tunnels and building plant

Quickstart

From the command line

Download profinetctl from GitHub Releases, or go install github.com/otfabric/profinetctl@latest. DCP and cyclic data are raw Ethernet, so most commands need root or CAP_NET_RAW on Linux, BPF access on macOS or Npcap on Windows:

# Which PROFINET devices are on eth0?
sudo profinetctl -i eth0 discover

# Name a new device (it has no name yet: select it by MAC) and give it an address
sudo profinetctl -i eth0 name set io-rack-1 --mac 00:0e:cf:12:34:56 --permanent
sudo profinetctl -i eth0 ip set 192.168.0.10/24 -s io-rack-1 --permanent

# Flash its LED to find it in the cabinet, then read identification and health
sudo profinetctl -i eth0 signal -s io-rack-1
sudo profinetctl -i eth0 im read -s io-rack-1
sudo profinetctl -i eth0 diagnostics -s io-rack-1

# Which device is plugged into which port?
sudo profinetctl -i eth0 topology

# Connect as IO-Controller with the device's GSDML file and watch its inputs
sudo profinetctl -i eth0 io monitor -s io-rack-1 --gsdml GSDML-V2.35-Vendor-Device-20240101.xml

Output is text, a table or JSON with stable exit codes. Commands that change a device say so, and reset needs --confirm.

From Go

go get github.com/otfabric/go-profinet

An IO-Controller and an IO-Device in one process, on the in-memory virtual Ethernet, so it needs no privileges (abridged from the go-profinet README):

network := vnet.New(1)
dn, _ := vnetenv.NewNode(network, 10, "192.168.0.10") // an endpoint with an IP stack
dev, _ := device.New(device.Config{
  Model: model, Mux: dn.Mux, StationName: "io-1",
  IP: suite("192.168.0.10"), ListenPacket: dn.Stack.ListenPacket,
})
cn, _ := vnetenv.NewNode(network, 1, "192.168.0.1")
ctrl, _ := controller.New(controller.Config{Mux: cn.Mux, ListenPacket: cn.Stack.ListenPacket, StationName: "plc-1"})
io1, _ := ctrl.AddDevice(controller.DeviceConfig{StationName: "io-1", Model: model})
_ = io1.WaitState(ctx, controller.StateRunning)

dev.SetInput(1, 1, []byte("PROFINET"), pnio.IOxSGood)
io1.SetOutput(2, 1, []byte{1, 2, 3, 4}, pnio.IOxSGood)
in, iops, _ := io1.Input(1, 1)

On a real network, osport.Open("eth0", ...) opens AF_PACKET, BPF or Npcap, and the expected configuration of a device usually comes from its GSDML file:

doc, err := gsdml.Parse(f)
m, err := gsdml.ToModel(doc, "") // the first device access point
d, err := ctrl.AddDevice(controller.DeviceConfig{StationName: "io-rack-1", Model: m})

What go-profinet and profinetctl support