Plugable USB2.0/UGA for 2 extended monitors on HP 520-1085uk

I have the following hardware:

Primary display - HP Touchsmart 520-1085uk running Win7
Secondary display - HP L1908W on DVI/VGA cable via plugable USB 2.0 to UGA adapter
Tertiary display - LG Flatron L1718S on VGA/VGA cable via plugable USB 2.0 UGA adapter

Both monitors/UGA adapters have individual USB 2.0 ports (i.e not hub’d).


  1. Unable to display 2nd and 3rd monitors at any on time.
  2. If the 2nd monitor is working, the 3rd will not display, however, if i unplug the 2nd monitor USB, the 3rd will activate and display correctly.
  3. Both USB 2.0/UGA adapters are showing blue lights and have been proven to work individually.
  4. 2 x Video display adapters are visible in the installed devices (device mgr)
  5. Displaylink S/W is installed correctly.

Other points:

  1. The HP 520 has a Radeon 6550A graphics card.
  2. WDP will not detect a new monitor even thought it is connected.
  3. Displaylink S/W and driver is up to date.
  4. There are 3 places where display properties can be modified: WDP, Displaylink and the AMD Catalyst S/W.
  5. Windows services - there is 1 instance of DisplayLinkService
  6. Windows processes - there is 1 instance of DisplayLinkManager.exe, DisplayLinkUI.exe and DisplayLinkUserAgent.exe

Please could you provide advice/solution for this issue. It seems to me that the USB bus only ever sees/allows active use of 1 adapter at a time,
almost like there is contention between the 2, 1 of the adapters takes precedence and if the active port is disconnected the other takes control of USB.



Hi Paul,

Thank you for contacting us about you USB Display adapters. I’m sorry you are having troubles with them.

We have a troubleshooting tool that helps us find out what is going on in situations like this. Please set up everything as you would normally use it, then go to this page and follow the instructions there:

You’ll have to send the resulting file to us directly at Please put “For TIcket #40590” in the subject line.

Thank you,
Plugable Support