What is USB upstream/downstream port on monitor ?

👤 Diwas Poudel    🕒 May 29 2022    📁 TECH

USB is an abbreviation for Universal Serial Bus. USB is an industry standard for short-distance communication, such as between a computer and a keyboard, a computer and a mouse, a monitor and a laptop, a printer and a computer, and so on. USB devices are now widespread due to the ease with which they can be configured and connected. The USB system has two types of ports: downstream and upstream. In this article, I will explain the Downstream and Upstream ports, as well as their applications in the monitor.

Before we get into those ports, there's one thing you should know. HDMI and RJ45 ports only send data to their respective devices, whereas USB ports can carry both power and data. Due to this USB gadgets do not need an extra cable for power.


Upstream Port

Upstream ports receive power and data from the host. The host in the case of a standalone monitor is a desktop PC / laptop, and a USB port is present in the standalone monitor. If a desktop PC or laptop is a Host, it usually has a Type A Connector, and an Upstream Port in a standalone monitor has a Type B Connector (ie. an upstream connector). These are linked using the cable below, which has both Type A and Type B ports.

upstream-downstream-cable and port
fig. Type A Downstream Port and Type B Upstream Port

As power and data are received by the monitor from Desktop PC / laptop so, the content of the laptop and desktop will be visible on the monitor. Therefore, the Upstream port is present in the monitor. This doesn't mean that the monitor does not require power. Monitors need extra AC mains cable to plug into an outlet. But if you consider thunderbolt and USB Type C port-based monitors which may not need extra power cable because they can drive enough power to an LCD monitor.

Some monitors have USB UP wrote on them, which represents the USB Upstream port and USB IN represents the USB Downstream port.

Upstream and Downstream is the USB hub feature of the monitor. It eliminates the need to run multiple cables from your monitor desk to your computer. Multiple cables connect to your monitor, and a single USB cable connects to your computer.

fig. LG Monitor Ports
Upstream Port are generally Type B Connector that receives power and data from the host.

Downstream Port

Downstream Port sends data and power to the devices like keyboard, mouse, standalone monitor, etc. In monitor there is a downstream port as well, if you want to connect peripherals like a mouse, keyboard, speaker, flash drive, etc then you can connect to the Downstream port present in Monitor. Downstream Port sends power and data to those external peripheral.USB supplies power at 5 V to power USB downstream devices.

Downstream Port is generally a Type-A connector that sends power and data to the peripherals or to the upstream port.

In most of the standalone hp and dell monitors, there is both upstream and downstream port available. The upstream port receives data and power from the host (generally desktop PCs or laptops). In these types of monitors, there should be a hub which connects the upstream port and downstream port. So, commonly there will only be one Upstream port and multiple Downstream ports in the monitor.

My Recommendation: If you want to connect a monitor for viewing the computer's video display then the USB port with Type A and Type B are not good. If the data port is Type C and Thunderbolt type then it is ok for video. Generally, prefer port for video is HDMI and DP.

Frequently Asked Questions:

Do I have to connect Keyboard, and Mouse to USB Downstream?

Ans: Yes, you will need to connect your keyboard and mouse to the downstream USB port on the monitor, and your computer should be connected to the upstream port. This gave the computer access to the keyboard, mouse, and other devices.

The upstream port is the one that connects to your computer, and the downstream ports are the ones into which you plug things like your keyboard, mouse, scanner, printer, etc. Therefore, think of the upstream port as the one that connects to your computer.

Why aren't my keyboard and mouse working on the monitor?

Ans: When you connect your keyboard to the downstream port of the monitor, the downstream ports are deactivated. This means that your external devices, such as your keyboard and mouse, are unable to function on the monitor. You can choose to perform either of these actions in order to activate the USB downstream.

  • Using the USB cable that was provided with the monitor, connect your computer to the USB upstream port on the monitor.
  • If the video source is a Thunderbolt 3, the USB downstream ports will be activated without any additional action required on the user's part..

Why monitor mostly has 1 upstream port and many downstream port?

Ans: The monitor only has one screen, and all of the information that is displayed on that screen comes from just one source. That source could be either your laptop or your computer. Consequently, you will need to connect your computer to the upstream port.

fig. Monitor having 1 upstream port and 2 downstream port

You are able to connect a variety of devices, such as a keyboard, mouse, scanner, printer, pen drive, joystick, and others, thanks to the many downstream ports that are available.


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