Adaptec USB2Xchange User Guide - Page 12

Introduction USB2Xchange Connectors The USB2Xchange is an integrated adapter with a 50-pin high-density connector at one end and a USB connector at the other, as shown in the figure below. 50-pin high-density SCSI connector USB connector The USB2Xchange adapter acts like a self-powered device- it receives its electrical power from attached SCSI devices. If no device is available, the adapter switches automatically to receive power from the USB bus. You may need to use an optional DC power supply in some rare cases-for example, if you're using an unpowered USB hub with attached SCSI devices that do not supply SCSI termination power. See Understanding the USB2Xchange Power Supply on page 21 for more information. Note: Adaptec strongly recommends that you plug the USB2Xchange adapter directly into a USB port on your system. If you must connect through a USB hub, use only a self-powered USB hub. Hot-Plugging The USB2Xchange adapter is hot-pluggable, which means you can connect and disconnect it from a live system. However, SCSI devices are not hot-pluggable. You must shut down your device and your computer before disconnecting a SCSI device from the USB2Xchange adapter. 2