USB Switching in AV Environments

USB is a popular standard that has been around since 1995. Its evolution has extended to the point where each of us utilizes this interface on a daily basis. USB ports are standard fixtures on computers and laptops with further extension recently onto other peripheral devices such as: keyboards, mice, printers, cameras, speakers, and of course storage devices like thumb drives. With all of this connectivity, it is no wonder that USB has permeated into AV environments and therefore must be accommodated into many installations.

The promise of USB

The availability of USB on so many electronic devices is testament to delivery of its promise – simplicity. Connectivity via the USB platform offers many significant conveniences and advantages in comparison to past approaches; namely, the time savings and lack of hardware/software device configuration when adding to a system. The plug-and-play approach simplifies connectivity while providing the capability for simultaneous communications between hosts and up to 127 attached peripheral devices. Host devices generally consist of a computer, or processing device, while peripherals comprise mass storage and HIDs – Human Interface Devices. Furthermore, standardized connectivity, cross-platform operation, and the ability to hot-swap allows for easy, straightforward accessibility.


USB-based components are commonly used in today’s AV systems, and the need to reliably switch USB signals continues to grow along with the evolution of the electronics industry. Three of the most popular USB centered applications include KVM –keyboard/video/mouse, interactive whiteboards, and annotator-based systems.

KVM – These applications revolve around the need to monitor, access, and operate multiple CPUs with a single keyboard, monitor, and mouse from a remote location. Many Command & Control centers incorporate this approach due to security aspects and available space within the operational area. The ability to house computers in a central secure location, while still being able to use them, is of great benefit.

Video annotation systems – A video annotator gives the user the ability to overlay text onto displayed video within a system. The user interface is pen-based, with touch screen monitors generally used as the writing surface. Video switchers are often used to switch multiple signals into the annotator with its output feeding a display. These systems are widely used in courtrooms and other corporate settings.

USB Connector Types
Connector types, Multiple connector types exist, but at the most basic levels, Type A connectors are utilized on Host devices, while Type B connectors are found on Peripherals.

Extron USB switching solutions

SW4 USB Plus

The SW USB Series were recently introduced to address the need for reliable USB switching. These products are loaded with integrator-friendly features that deliver streamlined design capability into any AV environment. The advanced feature set was designed specifically to address the specialized requirements of these systems, providing high reliability and flexible usability to suit the needs of these versatile environments.

  • Available in two and four input models
  • USB 2.0 compatibility allows the switcher to be used with peripheral devices meeting all current and past USB standards
  • Four-port output hub provides 5V, 500mA of power on each output for attachment of multiple peripheral devices
  • Port status LEDs provide visual confirmation of port activity for all connected and active host devices
  • Front panel, contact closure, and RS-232 control capabilities offers integration flexibility into a variety of control environments
  • RS-232 pass-through offers increased flexibility, allowing other Extron controllable switchers to be incorporated into designs that require additional signal switching
  • Host and peripheral emulation in the SW4 USB Plus provides "keep alive" functionality by continuously mimicking host and keyboard/mouse communications within the switcher. This emulation eliminates the need for enumeration, and reduces the chance of failed device communications throughout the switching process.
SW4 USB Diagram

Interactive whiteboards

Used extensively in education and corporate training environments, interactive whiteboards have become very popular over the past few years. Information written onto the whiteboard is electronically communicated to the host computer via USB connection. Classrooms and training labs often incorporate multiple PCs in association with video projection onto the board.