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NodalisEngine 1.0.12

NodalisEngine

NodalisEngine is a .NET Core 8.0 framework that executes JavaScript PLC programs produced by the Nodalis compiler. It embeds the Jint JavaScript engine, exposes IEC-61131-3 style function blocks, and provides fieldbus adapters (Modbus TCP and OPC UA) so your generated logic can talk to real hardware.

Highlights

• Drop-in runtime for the code emitted by nodalis-compiler.
• Extensible IO abstraction – implement just a few read/write methods in your host application.
• Built-in protocol clients for Modbus TCP and OPC UA plus hooks for custom transports.
• Integrated IEC function blocks (TON, TOF, TP, counters, logic gates, etc.).
• NuGet-friendly metadata so the library can be consumed from any net8.0 or higher application.

Installation

Use your preferred NuGet workflow:

# dotnet CLI
dotnet add package NodalisEngine

# or inside Package Manager Console
Install-Package NodalisEngine

NodalisEngine currently targets net8.0.

Getting Started

Create a host application that derives from NodalisEngine and wires the abstract IO operations to your hardware or simulator:

using Nodalis;

public class PlantEngine : NodalisEngine
{
 private readonly Dictionary<string, bool> _bits = new();
 private readonly Dictionary<string, ushort> _words = new();

 public override bool ReadBit(string address) => _bits.TryGetValue(address, out var value) && value;
 public override void WriteBit(string address, bool value) => _bits[address] = value;
 public override byte ReadByte(string address) => (byte)ReadWord(address);
 public override void WriteByte(string address, byte value) => WriteWord(address, value);
 public override ushort ReadWord(string address) => _words.TryGetValue(address, out var value) ? value : (ushort)0;
 public override void WriteWord(string address, ushort value) => _words[address] = value;
 public override uint ReadDWord(string address) => ReadWord(address);
 public override void WriteDWord(string address, uint value) => WriteWord(address, (ushort)value);
}

Then load and execute the PLC program that the Nodalis compiler produced:

var engine = new PlantEngine();
var javascript = File.ReadAllText("build/plc.js");
engine.Load(javascript);
engine.Setup();

while (true)
{
 engine.Execute(); // Runs the user logic
 engine.SuperviseIO(); // Polls any mapped IO clients
 await Task.Delay(10); // Adjust scan time as needed
}

Function blocks can be instantiated directly from the generated JavaScript, but you can also create them from .NET by calling CreateFunctionBlock("TON"), set inputs, and invoke Call().

IO Mapping & Protocol Clients

When you call mapIO(json) from the generated JavaScript (the compiler does this automatically), NodalisEngine instantiates the appropriate IOClient for each mapping. Two clients ship out of the box:

• ModbusClient – talks to Modbus TCP slaves and mirrors discrete/analog data into %I, %Q, %IW, %QW, etc.
• OPCClient – lets your runtime subscribe/publish to an OPC UA server.

You can extend the transport layer by overriding CreateClient(IOMap map) and returning your own IOClient implementation whenever a custom protocol identifier is encountered.

Integrated OPC UA Server

For vertical integration, you can expose the running PLC variables via the included OPCServer helper:

var opc = new OPCServer(engine);
opc.MapVariable("TankLevel", "%IW0");
opc.MapVariable("StartCommand", "%QX0.0");
await opc.StartAsync();

This spins up an OPC UA endpoint at opc.tcp://localhost:4840/UA/Nodalis using OPCFoundation.NetStandard.Opc.Ua. Each mapped variable mirrors values from your engine’s address space.

License

NodalisEngine is distributed under the Apache 2.0 license. See the headers inside the source files for details.

Changelog

[1.0.12] - 2026-05-04

• Added ability to set hostname for OPCServer.
• Added support for LWord types to OPCServer.
• Fixed problems with connecting to OPCServer

[1.0.9] - 2026-02-12

• Fixed TP function block.

[1.0.8] - 2026-02-11

• Fixed issue with constructing a FunctionBlock and calling "newStatic".

[1.0.4] - 2025-02-06

• Added support for Bacnet-IP.