86

I came across few configuration of a monitor and they include many different port along with some USB ports.

Monitor: DELL P2214H, DELL P2414H

In the monitor description it mentions that there are both USB 'upstream' and 'downstream' ports. What is the difference between these and what are the uses of each type? Can I connect a speaker directly to the monitor?

rivermont
  • 145
dotnetstep
  • 1,059

2 Answers2

85

On a monitor like that with USB ports, there is a USB HUB in the monitor itself. a USB hub has to have an input from the computer first.

enter image description here

http://en.wikipedia.org/wiki/USB

The TypeB the squared up connection is the input for the hub, a cable similar to a printer cable with a Type A plug on one side, and a Type B plug on the other side will be used to connect the computers USB port, to the hub. The hub will then have multiple ports.

enter image description here

Once you have an input run from the computer, the "HUB" will provide the USB ports. It will draw its power from the computer connection. Any USB connecting device would work in it, as long as it stays within the power specs.

Danijel
  • 714
  • 11
  • 26
Psycogeek
  • 9,038
  • 2
    This is what I am looking for. My main confusion is that if it has USB then does it play movie directly and if so How the voice will out of monitor as monitor I specified does not have audio functionality. – dotnetstep Dec 25 '14 at 04:24
  • No it is not like TVs that can have some internal Media chip for decoding and playing USB stick pictures and videos. in the computer monitors, so far they are just hubs , and that is all. – Psycogeek Dec 25 '14 at 04:27
  • good answer! Thanks. Accepted answers with "zero" upvotes always confuses me. How do people accept someone's answer and not upvote it? – Anmol Saraf Nov 06 '15 at 18:14
  • @ Psycogeek In this case if I want to connect this monitor to my computer via USB which I should use? – Manolo Sep 20 '16 at 11:22
  • 4
    If you want to connect a monitor for viewing the computers video display you should connect it via the DVI , the HDMI, DP or the VGA (as a last resort) USB is not really a video output device although you could use a USB video dongle to get to dvi or hdmi I do not really recommend it unless the data port is designed for Video like a thunderbolt or something. For doing uncompressed quality digital video out of the computer video cards, PCI linking things and onboard videos are good, USB tends to use a lot of cpu and bus speak to do that which it was not as designed to do. – Psycogeek Sep 22 '16 at 19:03
  • @psycogeek - I know this question is very old, but to update it to the modern age I was wondering - if you use USB-C to connect to monitor, is it possible for a USB-A or USB-B port on the monitor to send signal back through the USB-C port to the laptop? – Reilstein Jun 27 '21 at 22:15
  • @Reilstein Yes, in newer monitors the upstream USB port on the monitor is now often a USB-C port as they can carry more power and data. – sfxedit Nov 24 '22 at 18:05
  • Can I use a usb to hdmi converter, and use the downstream link to connect back to hdmi of the monitor? It might help eliminate 2 cables from my desktop/laptop. – Uzumaki D. Ichigo Jun 02 '23 at 05:42
  • The answer actually did not mention the terms "upstream" and "downstream" as stated in the OP's question - which is which and why? – Pontiac_CZ Jan 23 '24 at 12:06
18

USB ports carry both power and data to a device. There are two kinds of USB ports - upstream and downstream. An upstream USB port receives power (and data) and a downstream USB port provides power (and data) to devices connected to it.

USB ports in monitors allow you to connect additional USB devices (like keyboard, mouse, pen drive etc.) to your computer. But how can your computer know when you connect something to your monitor?

The computer provides video signals to the monitor through VGA or HDMI ports and cables. But these can't tell the computer when you connect a USB device to the monitor.

To use the USB ports on the monitor, you usually have to first connect a USB cable from your computer to the upstream USB port of the monitor. When you do this, the monitor will activate the other downstream USB ports and you can connect USB devices to use it with your computer.

In many newer monitors, the upstream USB port on the monitor is usually a USB-C port.

Thus, today, USB-C and Thunderbolt ports allow you to use a single cable between your computer and monitor to provide video signal to the monitor and also use USB ports on the monitor.

Thunderbolt ports, like USB, also carry both power and data. So if it is used to connect the computer with the Thunderbolt port on the monitor, then there is no need to connect the computer with the upstream USB port of your monitor with a separate USB cable. Using Thunderbolt port on a monitor will automatically activate the downstream USB port(s) on most monitors and the computer can use the devices connected to the monitor, through the Thunderbolt connection.

sfxedit
  • 333