USB connections have a maximum length of about 5 meters (16.4 feet). However, there are many situations in which the device (such as a BioNex, keyboard, or mouse) must be placed much further than that from the computer to which they are connected. One way of dealing with this distance is by using a USB extender, which sends the USB data over a CAT5 or CAT6 (Ethernet) cable to allow it to work over long distances. Even though it is using a standard network cable, the signals are different and it cannot be connected to normal network equipment.
USB extenders consist of 2 units: Transmit (LEX) and Receive (REX). The Transmit unit is found connected to the PC, which in the typical lab setup is found in the Control room. The Receive unit is typically found in the Subject room where the USB device is being used. The Receive unit is also connected to power via a provided AC power adapter.
For troubleshooting issues with USB extenders, or hardware connected to the USB extenders, please see this article.