Accessing a .NET abstract classes

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GS76 am 1 Dez. 2019

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Direkter Link zu dieser Frage

https://de.mathworks.com/matlabcentral/answers/494172-accessing-a-net-abstract-classes

Bearbeitet: GS76 am 19 Jan. 2020

Hi all,

I have created the following live script to access a .NET dll for the Micromeasurements P3 strain recorder and data logger.

I do not have experience with object-orientated programming and I have just come accross the following error message (in Italics), under the line of code "MMDeviceControl.DeviceInstance.

Error using MMDeviceControlLib.DeviceInstance

Abstract classes cannot be instantiated. Class 'MMDeviceControlLib.DeviceInstance' defines abstract methods

and/or properties.

Please see the class diagram for the .NET interface:

The vendor supplies a number of samples in C#. I have attached a zipped copy of the sample that I followed and it compiled 100% and ran, but I am unable to achieve the same in Matlab student version.

I have shown and attached the Matlab code as well as the MAT file, up to the point where I received the above error. I have also shown the C# code. I have indicated in the C# code where I am getting stuck duplicating this in Matlab. I have also attached a PDF copy of the live script.

Any assistance and advice with regards the above error would be appreciated.

MATLAB code

% Creating a global .NET assembly.
% File path of the *.dll.
filepath=uigetdir('C:\','Open directory where *.dll is located');
% Creating a .NET assembly.
MM_DotNet_DLL=NET.addAssembly([filepath '\MMDeviceControlLib.dll'])
import MMDeviceControlLib.*
import MMDeviceControlLib.MMDeviceInterface.*
New_Device_Interface=MMDeviceInterface 
New_Device_Interface.SetAllOpen(true);                 % Open all found devices
New_Device_Interface.ResetAllToFactoryDefaults(false); % Set all devices to default configuration settings (do not save to flash)
New_Device_Interface.SetAllActive(false);              % Set all existing channels to inactive
New_Device_Interface.SetAllShuntCal(false);            % Disable shunt calibration on all devices
MMDeviceControlLib.DeviceInstance

C# code

using MMDeviceControlLib;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
namespace Display_All_Channels
{
    class Program
    {
        
        /*
         * Sample program to configure and display all channels on all devices by polling the device interface for data
         * 
         */
        static void Main(string[] args)
        {
            try
            {
                Console.WriteLine("Creating interface and searching for devices...");
                using (MMDeviceInterface deviceInterface = new MMDeviceInterface())    //Create the device interface instance
                {
                    Console.WriteLine(string.Format("Found {0} devices", deviceInterface.DeviceInstances.Count()));
                    Console.WriteLine("Setting devices to open");
                    deviceInterface.SetAllOpen(true);                           //Open all found devices
                    deviceInterface.ResetAllToFactoryDefaults(false);           //Set all devices to default configuration settings (do not save to flash)
                    deviceInterface.SetAllActive(false);                        //Set all existing channels to inactive
                    deviceInterface.SetAllShuntCal(false);                      //Disable shunt calibration on all devices
                    foreach (DeviceInstance device in deviceInterface.DeviceInstances)
                    {
Get stuck!!             device.PoissonsRatio = 0.30;    //Poissons ratio is set at the device instance 
                    }
                    Console.WriteLine("Configuring and balancing (zeroing) channels...");
                    foreach (DeviceChannel channel in deviceInterface.Channels)
                    {
                        channel.Active = true;                                  //Set the channel to active
                        channel.BridgeType = BridgeType.UndefinedHalfQuarter;   //Set the bridge type
                        channel.EngUnits = "ue";                                //Set engineering units to micro-strain
                        channel.GaugeFactor = 2.0;                              //Gage factor to 2.0
                        channel.BalanceMode = BalanceMode.Auto;                 //Set the balance mode to auto
                        channel.BalanceValue = channel.ADReading;               //set the balance value to the current A/D reading
                    }
                    //Poll loop to read and display all available data until a any key is pressed
                    while (!Console.KeyAvailable)
                    {
                        foreach (double dataValue in deviceInterface.AllCurrentData)
                        {
                            Console.Write(string.Format("{0} ", dataValue));
                        }
                        Console.WriteLine();
                        Thread.Sleep(500);
                    }
                    Console.ReadKey();
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine(string.Format("Exception: {0}", ex.Message));
            }
            Console.WriteLine("Press any key to exit...");
            Console.ReadKey();
        }
    }
}