SumSymbolWrite Class

Inheritance Hierarchy

SystemObject
  SumCommandWrapperSumWrite
    SumSymbolCommandSumWrite
      TwinCAT.Ads.SumCommandSumSymbolWrite

Namespace: TwinCAT.Ads.SumCommand
Assembly: TwinCAT.Ads (in TwinCAT.Ads.dll) Version: 7.0.0+e56d35ccc4675faac24789a4aab60071fc61d470

C#

public class SumSymbolWrite : SumSymbolCommand<SumWrite>

The SumSymbolWrite type exposes the following members.

Methods

Remarks

The SumSymbolWrite implements symbolic write access with automatic (dynamic) value marshalling. The advantage of the symbolic access is (in contrast to the handle access classes SumHandleReadAnyType,SumHandleWriteAnyType) that all type information is available when using this ADS Sum Command. The disadvantage is, that the Symbolic information must be loaded beforehand, see examples. The SumSymbolWrite defaults to an IndexGroup/IndexOffset read (IndexGroupIndexOffset), because the the write access by InstancePath/SymbolName is not supported (for SumCommands). The disadvantage of this mode is, that dereferencing References/Pointers don't work and their values cannot be resolved. An option is to use the ValueByHandle, but that means to use more ADS roundtrips because the handles have to be requested first!

Usage of SumRead/SumSymbolWrite with AdsSession

/// <summary>
/// Defines the entry point of the application.
/// </summary>
/// <param name="args">The arguments.</param>
static async void Main(string[] args)
{
    Console.WriteLine("");
    Console.WriteLine("Press [Enter] for start:");
    Console.ReadLine();

    // Parse the command-line arguments
    AmsAddress address = ArgParser.Parse(args);

    CancellationTokenSource cancelSource = new CancellationTokenSource();
    CancellationToken cancel = cancelSource.Token;

    using (AdsSession session = new AdsSession(address))
    {
    // Connect to the device target.
    AdsConnection connection = (AdsConnection)session.Connect();

    // Load symbolic information
    var resultSymbols = await session.SymbolServer.GetSymbolsAsync(cancel);
    resultSymbols.ThrowOnError();

    ISymbolCollection<ISymbol> symbols = resultSymbols.Symbols;

    ISymbol bVar1 = symbols["GVL.bVar1"];
    ISymbol bVar2 = symbols["GVL.bVar2"];
    ISymbol projectName = symbols["TwinCAT_SystemInfoVarList._AppInfo.ProjectName"];

    SymbolCollection coll = new SymbolCollection() {bVar1, bVar2, projectName};

    // Sum Command Read
    SumSymbolRead readCommand = new SumSymbolRead(connection,coll, SumFallbackMode.All);
    var resultReadValues = await readCommand.ReadAsync(cancel);

    if (resultReadValues.Succeeded)
    {
        object[] values = resultReadValues.Values;

        for (int i = 0; i < coll.Count; i++)
        {
        Console.WriteLine("Symbol: {0} (Value: {1}, Type: {2})", coll[i].InstancePath, values[i].ToString(), values[i].GetType().Name);
        }
    }
    // Sum Command Write

    SumSymbolWrite writeCommand = new SumSymbolWrite(connection,coll, SumFallbackMode.All);
    object[] writeValues = new object[] {true, (short) 42, "MyNewProjectName"};

    var resultWrite = await writeCommand.WriteAsync(writeValues,cancel);
    }

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

Reference

TwinCAT.Ads.SumCommand Namespace ISumCommandSumSymbolWriteSumWriteBySymbolPath

Beckhoff Automation GmbH & Co. KG 2001-2026