Handling RMCLink.Interop .NET Assembly Errors

The RMCLink object uses .NET exceptions to report unexpected errors. Each RMCLink method's documentation lists the exceptions that it may throw. It should be pointed out that while many of these exceptions can be avoided while the program is being developed (e.g. ArgumentOutOfRangeException ), some can simply not be avoided at runtime. For example, if the communication cable is disconnected while a read or write is in progress, the communication will fail unexpectedly. Therefore, it is important that applications using RMCLink handle, at a minimum, the ConnectionNotMadeException and ReadWriteFailedException, and in multithreaded applications, CancelledException as well.

As is recommended for all .NET programming, exceptions should be caught specifically by type. You can then use the Message property to determine the root cause of the exception. For example, after catching a ConnectionNotMadeException, the Message property might tell you that the serial port is in use by another application.

Example

The following code example illustrates the proper use of .NET exceptions with the RMCLink.Interop assembly.

Visual Basic .NET

Imports RMCLinkNET
 
Module Module1
    Sub Main()
        Try
            Dim rmc As RMCLink = RMCLink.CreateEthernetLink(DeviceType.RMC70, "192.168.0.10")
 
            Console.WriteLine("Connecting...")
            rmc.Connect()
 
            Try
                Dim data() As Single = New Single(0) {}
 
                Console.WriteLine("Reading Axis 0 Actual Position...")
                rmc.ReadFFile(FileNumber70.fn70StatusAxis0, 8, data, 0, 1)
                Console.WriteLine(String.Format("  ActPos: {0:F3}", data(0)))
 
                Console.WriteLine("Done")
 
            Finally
                rmc.Disconnect()
            End Try
 
        Catch ex As ConnectionNotMadeException
            Console.WriteLine("Unable to connect to the controller. " & ex.Message)
        Catch ex As ReadWriteFailedException
            Console.WriteLine("Unable to read from the controller. " & ex.Message)
 
        End Try
    End Sub
End Module

using System;
using RMCLinkNET;
 
namespace Example
{
    public class Program
    {
        static void Main()
        {
            try
            {
                RMCLink rmc = RMCLink.CreateEthernetLink(DeviceType.RMC70, "192.168.0.10");
                Console.WriteLine("Connecting...");
                rmc.Connect();
                try
                {
                    float[] data = new float[1];
 
                    Console.WriteLine("Reading Axis 0 Actual Position...");
                    rmc.ReadFFile((int)FileNumber70.fn70StatusAxis0, 8, data, 0, 1);
                    Console.WriteLine(String.Format("  ActPos: {0:F3}", data[0]));
 
                    Console.WriteLine("Done");
                }
                finally
                {
                    rmc.Disconnect();
                }
            }
            catch (ConnectionNotMadeException e)
            {
                Console.WriteLine("Unable to connect to the controller. " + e.Message);
            }
            catch (ReadWriteFailedException e)
            {
                Console.WriteLine("Unable to read from the controller. " + e.Message);
            }
        }
    }
}

Visual C++/CLI

using namespace System;
using namespace RMCLinkNET;
 
int main()
{
    try
    {
        RMCLink^ rmc = RMCLink::CreateEthernetLink(DeviceType::RMC70, "192.168.0.10");
 
        Console::WriteLine("Connecting...");
        rmc->Connect();
        try
        {
            array<float>^ data = gcnew array<float>(1);
 
            Console::WriteLine("Reading Axis 0 Actual Position...");
            rmc->ReadFFile((int)FileNumber70::fn70StatusAxis0, 8, data, 0, 1);
            Console::WriteLine(String::Format("  ActPos: {0:F3}", data[0]));
 
            Console::WriteLine("Done");
        }
        finally
        {
            rmc->Disconnect();
        }
    }
    catch (ConnectionNotMadeException^ e)
    {
        Console::WriteLine("Unable to connect to the controller. " + e->Message);
    }
    catch (ReadWriteFailedException^ e)
    {
        Console::WriteLine("Unable to read from the controller. " + e->Message);
    }
    return 0;
}