FBWithString.cs

#region Copyright
//  
// Copyright (c) Phoenix Contact GmbH & Co. KG. All rights reserved.  
// Licensed under the MIT. See LICENSE file in the project root for full license information.  
//  
#endregion

using System;
using System.Iec61131Lib;
using Eclr;
using System.Runtime.InteropServices;
using Iec61131.Engineering.Prototypes.Types;
using Iec61131.Engineering.Prototypes.Variables;
using Iec61131.Engineering.Prototypes.Methods;
using Iec61131.Engineering.Prototypes.Common;

namespace ExampleLib
{
    // Define a string data type with a maximum string length of 200 characters
    // Size is string length + 4 byte header + 1 byte terminating zero + padding for two byte alignment
    // Mark the declaration with a String attribute and define the length
    [String(200)]
    [StructLayout(LayoutKind.Explicit, Size = 206)]
    public struct TString200
    {
        // Fields
        [FieldOffset(0)]
        public IecStringEx s;

        // Methods
        //ctor is needed to set the maximum size and called in the initialization
        public void ctor()
        {
            this.s.maximumLength = 200;
        }

        public void rctor()
        {
            this.s.maximumLength = 200;
        }
    }

    [FunctionBlock]
    public class FB_with_string
    {
        [Input]
        public IecString80 VALUE;
        [Input]
        public short MESSAGE_ID;
        [Output]
        public IecString80 RESULT1; // Standard string
        [Output]
        public TString200 RESULT2;  // User defined string

        [Initialization]
        public void __Init()
        {
            // Call ctor of strings in order to set the maximum size
            VALUE.ctor();
            RESULT1.ctor();
            RESULT2.ctor();
        }
    
        [Execution]
        public void __Process()
        {
            // Assign one IecString to another
            IecStringEx.Copy(ref VALUE.s, ref RESULT1.s);

            // assign .Net String to an IecString
            switch (MESSAGE_ID)
            {
                case 0:
                    RESULT2.s.Init("Nothing selected!");
                    break;
                case 1:
                    RESULT2.s.Init("The quick brown fox jumps over the lazy dog.");
                    break;
                case 2:
                    RESULT2.s.Init("The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog.");
                    break;
                default:
                    RESULT2.s.Init("Undefined message ID!");
                    break;
            }
        }
    }
    // Input and InOut parameter can be passed by reference. This saves memory and CPU time for copying values for large Arrays and structs.
    [FunctionBlock]
    public class FB_with_string2
    {
        [InOut]
        public unsafe IecStringEx* VALUE;
        [Input]
        public short MESSAGE_ID;
        [InOut]
        public unsafe IecStringEx* RESULT1;
        [InOut]
        public unsafe IecStringEx* RESULT2;

        [Initialization]
        public void __Init()
        {
            //Calling the ctor is not allowed when the string is passed by reference
            //at initialization time the pointer has no valid reference
        }

        [Execution]
        public void __Process()
        {
            unsafe
            {
                // Assign one IecString to another
                IecStringEx.Copy(ref *VALUE, ref *RESULT1);

                // assign .Net String to an IecString
                switch (MESSAGE_ID)
                {
                    case 0:
                        RESULT2->Init("Nothing selected!");
                        break;
                    case 1:
                        RESULT2->Init("The quick brown fox jumps over the lazy dog.");
                        break;
                    case 2:
                        RESULT2->Init("The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog.");
                        break;
                    default:
                        RESULT2->Init("Undefined message ID!");
                        break;
                }
            }
        }
    }
}