Device-Selective-Suspended is added as an option for USB-Serial adapter in Win11.

Important Notes:

If you see the following error in EZMQC for UltraScan Pro or UltraScan Vis when EZMQC idle for a while and have to reconnect sensor or restart EZMQC to reestablish the connection, the device-selective-suspended might be enabled in your windows.

How to Permanently Disable USB Selective Suspend for the UltraScan USB-Serial Adapter (Windows 11 / 10)

Recommended Method: Disable USB Power Saving in Device Manager

Steps

1. Right-click Start and select Device Manager

2. Expand Ports (COM & LPT)

3. Right-click your USB Serial Device (COMx) and select Properties

4. Open the Power Management tab

5. Uncheck:
   Allow the computer to turn off this device to save power

6. Click OK

Important (Highly Recommended)

Repeat the same steps for USB hubs:

1. In Device Manager, expand Universal Serial Bus controllers

2. For each USB Root Hub and Generic USB Hub:

   • Right-click → Properties

   • Open the Power Management tab

   • Uncheck Allow the computer to turn off this device to save power

   • Click OK

This resolves most USB-serial disconnection issues caused by Windows power-saving behavior.

Alternative Method: Disable USB Selective Suspend via Registry Editor

(Use only if the Power Management option is not available or the issue persists)

Steps

1. Log in to the PC using a Windows administrator account

2. Connect the instrument to the PC

3. Right-click Start → Device Manager

4. Expand Ports (COM & LPT) and note the COM port number
   (for example: COM4, COM5)

5. Press Win + R, type regedit, and press Enter
   (click Yes if prompted)

6. In Registry Editor, paste the following path into the address bar and press Enter: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\USB

7. Press Ctrl + F, type your COM port number exactly (for example, COM4), and click Find Next
   → This will take you to a folder ending with \Device Parameters

8. In the right-hand pane, look for SelectiveSuspendEnabled

   Case A – Entry exists

   Case B – Entry does not exist (very common)

   • Double-click SelectiveSuspendEnabled

   • Change the value from 1 to 0

   • Click OK

   • Right-click in the empty area → New → DWORD (32-bit) Value

   • Name it exactly:
     SelectiveSuspendEnabled

   • Double-click the new entry

   • Set Value data to 0

   • Click OK

9. Close Registry Editor

10. Restart the computer
    (Required – unplugging/replugging the cable is not sufficient)

After the restart, the USB-serial adapter will no longer enter sleep mode, and EZMQC should remain connected even after extended periods of inactivity.