Monitor works plugged in to UD-3900 that's chained to UD-CAM, but not directly

So the official support is great when I have a few hours to get logs, etc, but was hoping I could just get an answer to this specific question without doing a ton of diagnostics.

If a monitor works hooked up to a UD-3900 (HDMI cable to DVI adapter to UD-3900), why would that same monitor not work when attached to a UD-CAM (HDMI) plugged into the same laptop with the UD-3900 removed?

Even weirder, monitor works plugged into the UD-3900 plugged into a USB-A port on the UD-CAM plugged into the same laptop.

Are the drivers different somehow? What’s confusing the dock?

Okay, I said let’s pretend this is a hypothetical, but back in debug land, should I follow the DisplayLink cleaner instructions here? That’s reasonably close to what I’m seeing, though it’s a 5900.

(And is there a chance doing that would make the UD-3900 stop working with the monitor? If so, maybe I just leave things alone and keep the weird setup.)

Hi Ruffin,

Thanks for reaching out to Plugable support! I’d be happy to help with that.

In short, the UD-3900 docking station uses completely different type of technology for displays as the UD-CAM and they are not compatible together.

To expand on that, the UD-3900 utilizes DisplayLink technology to create display connections over standard USB 3.0 data connectivity. The only requirements for these display connections are essentially that the docking station has a DisplayLink chip inside and the computer has the drivers correctly installed.

On the other hand, the UD-CAM utilizes a direct USB-C connection referred to as Alt Mode, which is essentially a direct display connection to your computers internal graphics processor. This requires no drivers to be installed. However, it does require the computers internal hardware to support the Alt Mode connection through a USB-C port. Other ports on the docking station, such as the USB ports Ethernet and audio ports, only require USB 3.0 data and that explains why those are working while the display is not.

Without seeing any log files from the computer that you’re trying to use, I would assume that the computer does not support USB-C Alt Mode for allowing the UD-CAM to extend the display. I am happy to look up the specifications for the computer that you are using, if you would provide us with the exact make and model.

I would also mention that we would expect problems when connecting multiple docking stations to one host computer as this does tend to produce unpredictable conflicts.

I hope this information helps to explain the behavior that you’re seeing.

Thank you for giving us a chance to help and please let us know if you have any additional questions.

Richard A
Plugable Technologies

This topic was automatically closed 20 days after the last reply. New replies are no longer allowed.