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An Opc Library and a command line to perform OPC operations with ease and transparency among different protocols. Currently supports synchronous operation over UA and DA protocols.

Table of Contents


A nuget package is available for the library. To install H.Opc, run the following command in the Package Manager Console:

PM> Install-Package H.Opc

NOTE: Package was moved on from Hylasoft.Opc to H.Opc because of NuGet account issues

To install the command line interface, head to the release section.


to use the UA Client simply...

using (var client = new UaClient(new Uri("opc.tcp://host-url")))
  // Use `client` here

or with options...

var options = new UaClientOptions {
  UserIdentity = new Opc.Ua.UserIdentity("<your-username>", "<your-password>")
using (var client = new UaClient(new Uri("opc.tcp://host-url")), options)
  // Use `client` here

and to use the DA Client instead:

using (var client = new DaClient(new Uri("opcda://host-url")))
  // Use `client` here

Exploring the nodes

You can get a reference to a node with...

var node = client.FindNode("");

This will get you a reference to the node node in the folder

You can use the node reference to explore the hieriarchy of nodes with the properties Parent and SubNodes. For example...

Node parentNode = node.Parent;
IEnumerable<Node> children = client.ExploreFolder(node.Tag);
IENumerable<Node> grandChildren = children.SelectMany(m => client.ExploreFolder(m.Tag));

Read a node

Reading a variable? As simple as...

var myString = client.Read<string>("").Value;
var myInt = client.Read<int>("").Value;

The example above will read a string from the tags string and num in the folder

Writing to a node

To write a value just...

client.Write("", "My new value");
client.Write("", 42);

Monitoring a tag

Dead-simple monitoring:

client.Monitor<string>("", (readEvent, unsubscribe) =>
  if(ThatsEnough == true)

The second parameter is an Action<T, Action> that has two parameter:

  • readEvent contains all the information relevant to the event such as timestamps, quality and the value
  • unsubscribe is a function that unsubscribes the current monitored item. It's very handy when you want to terminate your callback

it's important that you either enclose the client into a using statement or call Dispose() when you are finished, to unsubscribe all the monitored items and terminate the connection!

Go Asynchronous!

Each method as an asynchornous counterpart that can be used with the async/await syntax. The asynchronous syntax is recommended over the synchronous one (maybe the synchronous one will be deprecated one day).

Command line

You can also use the command line interface project to quickly test your an OPC. Build the h-opc-cli project or download it from the release page of this repository, then run:

h-opc-cli.exe [OpcType] [server-url]

Where OpcType is the type of opc to use (e.g: "UA", "DA"). Once the project is running, you can use the internal command to manipulate the variable. To have more information aboute the internal commands, type help or ?

Build + Contribute

The repository uses cs-boilerplate. Read the readme of the cs-boilerplate repository to understand how to build, run tasks and commit your work to master.

Unit Testing

  • The unit tests rely on locally running simulator OPC servers. The ones used in this project are OPC Foundation's Sample Server and Graybox Simulator
    • You must download OPC Foundation's Sample Server from the OPC Foundation website (link above), but GrayBox can be downloaded using Chocolatey
      • choco install grayboxsimulator
    • OPC Foundation's Sample Server requires you register with the website before you can download.
  • The tests use NUnit. To run them in Visual Studio, install the NUnit 3 Test Adapter
  • To configure the test project, run the configure.ps1 script in the root h-opc directory


  • Open OPC Foundation's Sample Client (under Start -> OPC Foundation -> UA x.xx -> Sample Applications -> Opc.Ua.SampleClient.exe)
    • This will start the server too
    • Running tests will only work with this program open


  • With Graybox Simulator installed, tests should automatically work


The following binaries belong to the OPC Foundation. You must become a registered user in order to use them:

  • OPC.Ua.Client.dll
  • OPC.Ua.Core.dll
  • OPC.Ua.Configuration.dll
  • OpcComRcw.dll
  • OpcNetApi.Com.dll
  • OpcNetApi.dll

You must agree to the terms and condition exposed on the OPC Foundation website. Hyla Soft is not responsible of their usage and cannot be held responsible.


  • Add promise-based asynchronous calls

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OPC client made simpler, for UA and DA, and OPC UA Server. Forked from hylasoft-usa on github spread retract


No release




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