The KVM (Keyboard, Video, and Mouse) feature allows users to control multiple computers using a single keyboard, mouse, and monitor. When a monitor has an integrated KVM switch, it enables seamless switching between two computer hosts, managing display signals and USB peripherals (e.g., a keyboard and mouse).
Explanation of Port Functions
The example above has USB-A, USB-B, Type-C, HDMI, and DisplayPort ports. Below, we will explain the function of each port within the scope of KVM switches before we get to some example scenarios.
USB-B (Upstream USB Data)
- Function: The USB-B port on a monitor acts as an upstream interface, meaning it allows the monitor to receive data from a computer or other device.
- Common Use: This connection is primarily used to link the monitor to a computer's USB port to enable the use of the monitor's built-in USB hub.
- Benefit: Once connected, the USB-A ports on the monitor (downstream) can be used to connect peripherals like a keyboard, mouse, or USB drives.
- Connector Type: Typically, a square-shaped port (USB-B), often seen with printers and other devices.
USB-A (Downstream USB Data)
- Function: The USB-A ports on a monitor act as downstream interfaces, which allow peripherals to connect to the monitor and, indirectly, to the computer through the USB-B or USB-C upstream connection.
- Common Use: Devices such as keyboards, mice, external drives, and USB headsets can be plugged into these ports.
- Benefit: The monitor acts as a USB hub, reducing the need for additional USB ports on the computer itself.
USB-C (Full Functionality)
- Function: A full-featured USB-C port supports multiple data types:
- Upstream USB Data: Sends USB signals to the computer, enabling the monitor’s USB hub functionality.
- Transmit Audio and Video Data: Capable of delivering high-resolution video and audio signals (like HDMI/DP), making it versatile for display and USB connections simultaneously.
- Power Delivery (PD): Often capable of charging laptops or other devices while transmitting data and video (depending on monitor specifications).
- Benefit: A single USB-C cable can handle video, audio, USB data, and power, significantly reducing cable clutter.
HDMI/DP (Transmit Audio and Video Data)
- Function: Both HDMI (High-Definition Multimedia Interface) and DP (DisplayPort) are dedicated ports for transmitting audio and video signals from a computer or other device to the monitor.
- Key Points:
- HDMI is commonly used in consumer electronics (e.g., TVs, gaming consoles).
- DisplayPort (DP) is often preferred for computer monitors because of its support for higher refresh rates and resolutions.
- Limitation: HDMI and DP ports cannot transmit USB data, so additional USB cables (e.g., USB-B or USB-C) are required to enable peripheral connectivity and KVM features.
Summary of Connections:
- USB-B: Receives USB data for the monitor’s hub functionality.
- USB-A: Provides downstream USB connections for peripherals.
- USB-C: Handles upstream USB data, video, audio, and often power delivery.
- HDMI/DP: Transmit video and audio signals but do not support USB data transfer.
Requirements for the KVM Feature
- Hardware and Software Requirements:
- The monitor must have at least two USB upstream interfaces (usually USB Type-B or USB-C) and built-in support for the KVM feature.
- Advanced monitors may include full-featured USB-C interfaces that transmit USB data, audio, and video signals.
- Connections:
- HDMI or DisplayPort interfaces cannot carry USB data signals, so connecting the monitor’s USB upstream ports to the corresponding USB ports on the computers is necessary.
- Users must ensure the correct setup of video and USB data connections for both computer hosts.
For example, the upstream interfaces are as follows:
- First upstream interface: USB-B + HDMI/DisplayPort.
- Second upstream interface: Full-featured USB-C.
Practical Examples
Case 1: One Laptop with USB-C and One Desktop without USB-C
Cables Required:
- One double-ended USB-C data cable.
- One USB-A to USB-B data cable.
- One HDMI/DisplayPort video cable.
Steps for Connection:
- Connect the laptop to the monitor using the USB-C cable.
- Connect the desktop to the monitor using an HDMI/DisplayPort cable.
- Connect the desktop’s USB-A port to the monitor’s USB-B port using the USB-A to USB-B cable.
- Plug the keyboard and mouse into the monitor’s USB-A ports.
KVM Switching: In this configuration, the audio/video and USB data signals are automatically bound to the USB-C interface by default. To switch between the two devices:
- Simply change the monitor’s input source (e.g., from USB-C to HDMI/DP).
- The keyboard and mouse will switch automatically to the active device.
Case 2: Two Desktops Without USB-C
Cables Required:
- One USB-C to USB-A data cable (or a double-ended USB-C if supported).
- One USB-A to USB-B data cable.
- Two HDMI/DisplayPort video cables.
Steps for Connection:
- Connect Host 1 to the monitor using a USB-C to USB-A cable or a double-ended USB-C cable.
- Connect Host 2 to the monitor using a USB-A to USB-B cable.
- Connect both Hosts to the monitor using their respective HDMI/DisplayPort cables.
- Plug the keyboard and mouse into the monitor’s USB-A ports.
KVM Switching: In this scenario, since neither computer transmits video/audio data over USB-C:
- You must use the monitor’s OSD (On-Screen Display) menu to manually switch the USB HUB signal source.
- Change the display input source as needed to view the correct device.
Pros and Cons of the KVM Feature
- Advantages: The KVM feature allows users to manage multiple systems with a single set of peripherals, which is ideal for tasks requiring frequent switching (e.g., 3D rendering, video production, and office work).
Limitations: The monitor cannot display video signals from two computers simultaneously, as KVM is designed for switching rather than multi-view.