AdsSession Class

Inheritance Hierarchy

System.Object
  TwinCAT.Session
    TwinCAT.Ads.AdsSession
Namespace:  TwinCAT.Ads
Assembly:  TwinCAT.Ads (in TwinCAT.Ads.dll) Version: 4.3.0.0

C#

public class AdsSession : Session, IAdsSession, 
    ISession, IConnectionStateProvider

VB

Public Class AdsSession
    Inherits Session
    Implements IAdsSession, ISession, IConnectionStateProvider

The AdsSession type exposes the following members.

Constructors

Properties

Methods

Events

Fields

Remarks

On top of the well known TcAdsClient class that is used traditionally for ADS communication, the AdsSession class provides the following additionally abilities out of the box: These are used to provide more stable connections to ADS Servers than the TcAdsClient can provide. The main issues are Resurrection / Self-Healing after communication timeouts, faster and less error prone reaction to communication errors (not necessarily waiting for communication timeouts) und enhanced communication diagnosis. These enhanced features are provided by the following additions to the TwinCAT.Ads API:

• AdsConnection class.
• Enhanced diagnosis in form of communication statistics Statistics
• (semi-automatic) Resurrectable client communication with AdsConnection objects.
• Symbol caching SymbolServer
• Fail fast handler for connection stabilization IFailFastHandler

The AdsConnection is established by calling the Connect. method. The returned AdsConnection can be used as long the AdsSession exists.

Examples

The following sample shows a simple use of the AdsSession object. The AdsSession object (and the dynamic SymbolLoader features) are only available from .NET 4 and upwards.

Use of the AdsSession object

using System;
using System.Diagnostics;
using System.Threading;

using TwinCAT;
using TwinCAT.Ads;
using TwinCAT.Ads.TypeSystem;
using TwinCAT.TypeSystem;
using TwinCAT.TypeSystem.Generic;

namespace Sample
{
    class Session
    {
    /// <summary>
    /// Defines the entry point of the application.
    /// </summary>
    /// <param name="args">The arguments.</param>
    static void Main(string[] args)
    {
        AmsAddress address = ArgParser.Parse(args);
        SessionSettings settings = SessionSettings.Default; // Default settings are Async access with Timeout 5 sec

        // Async access is necessary for Console applications!

        using (AdsSession session = new AdsSession(address, settings))
        {
        AdsConnection connection = (AdsConnection) session.Connect(); // Establish the connection
        connection.ConnectionStateChanged += Connection_ConnectionStateChanged;

        ConnectionState connectionState = connection.ConnectionState; // The actual connection state

        // Read the identification and version number of the device
        DeviceInfo deviceInfo = connection.ReadDeviceInfo();
        Version version = deviceInfo.Version.ConvertToStandard();
        Console.WriteLine(string.Format("DeviceName: {0}", deviceInfo.Name));
        Console.WriteLine(string.Format("DeviceVersion: {0}", version.ToString(3)));

        /// Read the state of the device
        StateInfo stateInfo = connection.ReadState();
        AdsState adsState = stateInfo.AdsState;

        short deviceState = stateInfo.DeviceState;
        Console.WriteLine(string.Format("DeviceState: {0}", deviceState));
        Console.WriteLine(string.Format("AdsState   : {0}", adsState));

        // Other ADS methods (as formerly used on TcAdsClient) can be used also on connection object:

        // connection.Read(...)
        // connection.Write(...)
        // connection.AddDeviceNotificationEx += ...


        // Session communication Diagnostic:

        int resurrectionTries = connection.ResurrectingTries;
        int succeededResurrections = connection.Resurrections;

        AdsCommunicationStatistics statistics = session.Statistics; // The communication statistics

        // Symbol access:
        // The Session holds and Caches the Symbolic data information
        ReadOnlyDataTypeCollection types = session.SymbolServer.DataTypes;
        ReadOnlySymbolCollection symbols = session.SymbolServer.Symbols;

        dynamic projectNameSymbol = symbols["TwinCAT_SystemInfoVarList._AppInfo.ProjectName"];
        string projectName = (string) projectNameSymbol.ReadValue();

        // Or use dynamic objects
        dynamic appInfo = symbols["TwinCAT_SystemInfoVarList._AppInfo"];
        string projectName2 = appInfo.ProjectName.ReadValue();

        Console.WriteLine("");
        Console.WriteLine("Press [Enter] for leave:");
        Console.ReadLine();
        }
    }

    private static void Connection_ConnectionStateChanged(object sender, ConnectionStateChangedEventArgs e)
    {
        Console.WriteLine("Connection State changed (NewState: {0}, OldState: {1}",e.NewState,e.OldState);
    }

Reference

TwinCAT.Ads Namespace

TwinCAT.Session

TwinCAT.Ads.IAdsSession

IInterceptionFactory