TitaniumAS.Opc.Client

Open source .NET client library for OPC DA. The library provides you with .NET COM wrappers for OPC DA interoperability.

Features

• Support of local and network OPC DA servers.
• Support of OPC DA 1.0, 2.05A, 3.0.
• Browsing of OPC DA servers.
• Async/await in read and write operations.
• Subscription to data changes via .NET events.
• Support of server shutdown events.
• Easy resource management.

Installation

Run the following command in the NuGet Package Manager console:

PM> Install-Package TitaniumAS.Opc.Client

See NuGet package.

Basic usage

The following examples cover basic usages of the library. Assume you have an application with installed NuGet package of the library.

Bootstrapping the library

Call Bootstrap.Initialize() in the start of your application. An application process should be started under MTA apartment state due to CoInitializeSecurity call during the library initialization. See explanation.

Connecting to an OPC DA server

You should create OPC DA server instance first and then connect to it.

// Make an URL of OPC DA server using builder.
Uri url = UrlBuilder.Build("Matrikon.OPC.Simulation.1");
using (var server = new OpcDaServer(url))
{
    // Connect to the server first.
    server.Connect();
    ...
}

Browsing elements

You can browse all elements of any OPC DA servers versions with OpcDaBrowserAuto.

// Create a browser and browse all elements recursively.
var browser = new OpcDaBrowserAuto(server);
BrowseChildren(browser);
...

void BrowseChildren(IOpcDaBrowser browser, string itemId = null, int indent = 0)
{
    // When itemId is null, root elements will be browsed.
    OpcDaBrowseElement[] elements = browser.GetElements(itemId);

    // Output elements.
    foreach (OpcDaBrowseElement element in elements)
    {
        // Output the element.
        Console.Write(new String(' ', indent));
        Console.WriteLine(element);

        // Skip elements without children.
        if (!element.HasChildren)
            continue;

        // Output children of the element.
        BrowseChildren(browser, element.ItemId, indent + 2);
    }
}

Creating a group with items

You can add a group with items to the OPC DA server.

// Create a group with items.
OpcDaGroup group = server.AddGroup("MyGroup");
group.IsActive = true;

var definition1 = new OpcDaItemDefinition
{
    ItemId = "Random.Int2",
    IsActive = true
};
var definition2 = new OpcDaItemDefinition
{
    ItemId = "Bucket Brigade.Int4",
    IsActive = true
};
OpcDaItemDefinition[] definitions = { definition1, definition2 };
OpcDaItemResult[] results = group.AddItems(definitions);

// Handle adding results.
foreach (OpcDaItemResult result in results)
{
    if (result.Error.Failed)
        Console.WriteLine("Error adding items: {0}", result.Error);
}
...

Reading values

Items of a group can be read either synchronously or asynchronously.

// Read all items of the group synchronously.
OpcDaItemValue[] values = group.Read(group.Items, OpcDaDataSource.Device);
...

// Read all items of the group asynchronously.
OpcDaItemValue[] values = await group.ReadAsync(group.Items);
...

Writing values

Also items of a group can be written either synchronously or asynchronously.

// Prepare items.
OpcDaItem int2 = group.Items.FirstOrDefault(i => i.ItemId == "Bucket Brigade.Int2");
OpcDaItem int4 = group.Items.FirstOrDefault(i => i.ItemId == "Bucket Brigade.Int4");
OpcDaItem[] items = { int2, int4 };

// Write values to the items synchronously.
object[] values = { 1, 2 };
HRESULT[] results = group.Write(items, values);
...

// Write values to the items asynchronously.
object[] values = { 3, 4 };
HRESULT[] results = await group.WriteAsync(items, values);
...

Getting values by subscription

A group can be configured for providing a client with new values when they are changed.

// Configure subscription.
group.ValuesChanged += OnGroupValuesChanged;
group.UpdateRate = TimeSpan.FromMilliseconds(100); // ValuesChanged won't be triggered if zero
...

static void OnGroupValuesChanged(object sender, OpcDaItemValuesChangedEventArgs args)
{
    // Output values.
    foreach (OpcDaItemValue value in args.Values)
    {
        Console.WriteLine("ItemId: {0}; Value: {1}; Quality: {2}; Timestamp: {3}",
            value.Item.ItemId, value.Value, value.Quality, value.Timestamp);
    }
}

Troubleshooting

• Check Opc Core Components (https://opcfoundation.org/developer-tools/developer-kits-classic/core-components) installed on your system first. It is possible you have not installed OPCEnum service.
• To run unit tests in NUnit, it should be configured with x86 envirenment.
• In Visual Studio, set your project to use "Prefer 32-bit". Project Properties → Build → "Prefer 32-bit" in Platform target. The code should be compiled as 32-bit.

API documentation

Comming soon...

License

The MIT License (MIT) – LICENSE.