EtherNet/IP

The EtherNet/IP module targets Allen-Bradley / Rockwell PLCs. It supports Register Session, SendRRData, CIP Read Tag / Write Tag, and Get Attribute Single / Set Attribute Single over TCP 44818. Current coverage focuses on scalar tags for point acquisition and write-back.

Start with a Virtual PLC

var memory = new EtherNetIpSlaveMemory();
memory.SetTag("Temperature", EtherNetIpDataType.Int, (short)253);
memory.SetTag("Running", EtherNetIpDataType.Bool, true);

await using var app = ZeusHost.Create(builder =>
{
    builder.AddAcquisition(TimeSpan.FromMilliseconds(100));
    builder.AddVirtualChannel("enip-link", new EtherNetIpSlaveResponder(memory));
    builder.AddEtherNetIp("plc", "enip-link", points: map => map
        .Int("temperature", "Temperature", scale: 0.1).Writable("temperature")
        .Bool("running", "Running").Writable("running"));
});

await app.StartAsync();
var temperature = app.Points.Get<double>("temperature");
await app.Points.WriteAsync("temperature", 18.6);

Run sample: samples/Zeus.Samples.Console.EtherNetIp.

Connect to a Real PLC

await using var app = ZeusHost.Create(builder =>
{
    builder.AddTcpClient("enip-link", "192.168.1.10", 44818);
    builder.AddEtherNetIp("plc", "enip-link", points: map => map
        .Int("temperature", "Temperature", scale: 0.1)
        .Bool("running", "Running"));
});

Use the full PLC tag path for Program-scope tags, for example Program:Main.Speed.

Read/Write API

var plc = app.Devices.Get<EtherNetIpDevice>("plc");

var temperature = await plc.ReadTagAsync("Temperature", EtherNetIpDataType.Int, scale: 0.1);
await plc.WriteTagAsync("Temperature", EtherNetIpDataType.Int, 18.6, scale: 0.1);

var running = await plc.ReadTagAsync("Running", EtherNetIpDataType.Bool);
await plc.WriteTagAsync("Running", EtherNetIpDataType.Bool, true);

byte[] identityName = await plc.GetAttributeSingleAsync(classId: 0x01, instanceId: 1, attributeId: 7);
await plc.SetAttributeSingleAsync(classId: 0x64, instanceId: 1, attributeId: 3, new byte[] { 0x01 });

Scalar Types

JSON / API	CIP type
bool / Bool	BOOL 0x00C1
sint / SInt	SINT 0x00C2
int / Int	INT 0x00C3
dint / DInt	DINT 0x00C4
lint / LInt	LINT 0x00C5
usint / USInt	USINT 0x00C6
uint / UInt	UINT 0x00C7
udint / UDInt	UDINT 0x00C8
ulint / ULInt	ULINT 0x00C9
real / Real	REAL 0x00CA
lreal / LReal	LREAL 0x00CB

Points

builder.AddEtherNetIp("plc", "enip-link", points: map => map
    .Int("temperature", "Temperature", scale: 0.1).Writable("temperature")
    .DInt("speed", "Program:Main.Speed")
    .Real("flow", "Flow")
    .Bool("running", "Running").Writable("running"));

Point names can be business-friendly even when PLC tag paths are longer. scale applies only to numeric tags; BOOL points cannot use scale or alarm limits.

JSON Configuration

{
  "channels": [
    { "name": "enip-link", "type": "tcp", "host": "192.168.1.10", "port": 44818 }
  ],
  "devices": [
    {
      "name": "plc",
      "channel": "enip-link",
      "type": "ethernet-ip",
      "points": [
        { "name": "temperature", "tag": "Temperature", "dataType": "int", "scale": 0.1, "writable": true },
        { "name": "running", "tag": "Running", "dataType": "bool", "writable": true },
        { "name": "speed", "tagName": "Program:Main.Speed", "dataType": "dint" }
      ]
    }
  ]
}

Virtual EtherNet/IP PLC:

{ "name": "enip-link", "type": "virtual", "responder": "ethernet-ip" }

If tag / tagName is omitted, Zeus uses the point name as the PLC tag name.

Common Issues

Symptom	Likely cause	Fix
Timeout	TCP 44818, firewall, or PLC EtherNet/IP service unavailable	Test with EtherNetIpSlaveResponder, then check the field network
CIP status 0x04	Tag path is wrong or missing	Check tag path, Program scope, and casing
Type mismatch	Configured dataType differs from PLC tag type	Match the PLC project type
Write-back missing	Point not writable or PLC tag is read-only	Mark writable and confirm PLC permissions
BOOL has scale/alarm	BOOL is not numeric	Remove scale, lowAlarmLimit, and highAlarmLimit

Next: Points and Acquisition.