Wake remote display RRS feed

  • Question

  • I have the following code that allows my to control the power of the monitor.

    using System;
    using System.Runtime.InteropServices;
    using System.Windows.Forms;
    namespace MonPwr
        public partial class HiddenForm : Form
            // ReSharper disable InconsistentNaming
            private const int WM_SYSCOMMAND = 0x0112;
            private const int SC_MONITORPOWER = 0xF170;
            // ReSharper restore InconsistentNaming
            private static extern int SendMessage(int hWnd, int hMsg, int wParam, int lParam);
            public HiddenForm(bool power)
                SendMessage(Handle.ToInt32(), WM_SYSCOMMAND, SC_MONITORPOWER, power ? -1 : 2);
                Load += HiddenForm_Load;
            private void HiddenForm_Load(object sender, EventArgs e)
            protected override void OnLoad(EventArgs e)
                Visible = false;
                ShowInTaskbar = false;

    This code work fine if I execute it locally, but if I copy the application to a remote machine and execute it using the Win32_Process.Create() method, it doesn't do anything. I can see the process fleetingly appear in Task Manager, although nothing happens. If I execute the process locally on that same machine, again it works fine.

    I've outputted the return code from SendMessage() to a text file, and it is returning 0.

    Is this because the process is running non-interactively?

    I've also tried using Scheduled Tasks and PSExec without success.

    • Edited by sw3103 Tuesday, March 10, 2015 3:28 PM
    Tuesday, March 10, 2015 3:27 PM


All replies

  • Not authoritative, but looks like this developer went down the same path. See the 'Architecture' section

    This is really a Win32 question, so I'd post there, e.g.

    • Marked as answer by sw3103 Wednesday, March 11, 2015 4:55 PM
    Tuesday, March 10, 2015 9:25 PM
  • Hi sw3103,

    I have tested your code on remote machine, yes it shows nothing. Very wierd. Never seen that. I doubt Win32SendMessage has some limitation.

    After search with other way to implement this. Using lockworkstation (user32) both works on local machine and remote machine. Please try and test.

      [DllImport("user32.dll", SetLastError = true)]
            static extern bool LockWorkStation();
       private void HiddenForm_Load(object sender, EventArgs e)
               // Close();

    Have a nice day!


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    Wednesday, March 11, 2015 7:55 AM
  • Thank you. I read the Architecture section, and it's headed me down the correct path to getting this process running in the active session.

    I have managed to get this working using PsExec.exe with the -i switch. Not sure why it didn't work for me previously, but it's all working now.

    Wednesday, March 11, 2015 4:55 PM