Access by variable name

Requirements

Description

The following program accesses a PLC variable that does not have an address. Access must therefore be made by the variable name. Once the PLC variable in the example program exceeds 10 it is reset to 0:

C# program

static void Main(string[] args)
{
 //Create a new instance of class TcAdsClient
 TcAdsClient tcClient = new TcAdsClient();
 AdsStream dataStream = new AdsStream(4);
 AdsBinaryReader binReader = new AdsBinaryReader(dataStream);

 int iHandle = 0;
 int iValue = 0;

 try
 {
    // Connect to local PLC - Runtime 1 - TwinCAT 3 Port=851
    tcClient.Connect(851);
    
    //Get the handle of the PLC variable "PLCVar"
    iHandle = tcClient.CreateVariableHandle("MAIN.PLCVar");

    Console.WriteLine("Press enter to continue and any other key to abort..");

    do
    {
     //Use the handle to read PLCVar
     tcClient.Read(iHandle, dataStream);
     iValue = binReader.ReadInt32();
     dataStream.Position = 0;

     Console.WriteLine("Current value is: " + iValue);

     if (iValue >= 10)
     {
        //Reset PLC variable to zero
        tcClient.WriteAny(iHandle, 0);
     }

    } while (Console.ReadKey().Key.Equals(ConsoleKey.Enter));
 }
 catch (Exception ex)
 {
    Console.WriteLine(ex.Message);
    Console.ReadKey();
 }
 finally
 {
    //Delete variable handle
    tcClient.DeleteVariableHandle(iHandle);
    tcClient.Dispose();
 }
}