Video Cables Untangled

Many Plugable products, like our USB docking stations and USB video adapters, allow you to connect additional displays to your system. However, deciding which cable types to use for those displays can be confusing. I will try to clarify the situation in this post.

The image below shows the back of our UD-3900 USB docking station. Let’s use it as an example.

I’ve labeled the UD-3900’s two video outputs. One is a HDMI; the other is DVI. When designing this dock we put a lot of thought into these outputs, wanting to give our customers as many options as possible for connecting different displays. We arrived at these two because many types of cables can be attached. Let’s look at a few examples.

The most commonly used cables are standard DVI and HDMI cables (photos below). “Standard” means the cable has the same connector on each end. These cables should always work with the dock as long as the cable itself is not faulty. When troubleshooting a display problem, the first step is to check that the cables are connected securely and if possible swap them with ones that are known to be good.

There are other options besides standard HDMI and DVI cables. A DVI to VGA adapter is included with the UD-3900 that can connect the dock to an older monitor with VGA inputs using a standard VGA to VGA cable.

Although not included with the docking station, you can also use an HDMI to DVI cable to connect a DVI display. Although we don’t make a cable like that ourselves, many of our customers have successfully used one like this: www.amzn.com/B00K7HECTQ/

A nice thing about this type of cable is that it is bidirectional, which means it can work in both directions. It can go from the HDMI port on the dock to the DVI input of a display or from the DVI port on the dock to a HDMI display. If needed, you can also use Plugable’s optional HDMI-VGA cable (http://www.plugable.com/products/hdmi-vga) to connect the HDMI port to a VGA display.

So what does this all mean? Out of the box, our UD-3900 dock can connect three types of displays: HDMI, VGA or DVI, and by using various cable and adapters you can
adapt these outputs to your particular setup. You can have two HDMI displays, two DVI displays, two VGA or any combination of those.

Now that we have seen what does work, how about some examples of what does NOT work?

I mentioned earlier that you can convert the HDMI output to DVI and vice-versa, but there is an important point to note: HDMI output can carry an audio signal, but DVI output cannot. Why does this matter? If you convert the HDMI output of the dock to DVI you will lose the audio. By the same token, if you convert the DVI output to HDMI, it cannot carry audio as that information was not present to begin with.

There is a common misconception about converting HDMI to DisplayPort. Although there are simple cables with an HDMI connector on one end and a DisplayPort connector on the other, they will not work with Plugable docking stations. This is because they are usually passive cables that only convert DisplayPort output to HDMI and not the other direction. Differences between the two standards only allow for this unidirectional conversion.

Although somewhat complex, I hope this information will help untangle the many cabling possibilities when using our products. Please let us know if you have any questions in the comments below!