Adaptec USB2Xchange User Manual

Contents

21Understanding the USB2Xchange Power SupplyUnderstanding theUSB2Xchange Power SupplyThe USB2Xchange adapter receives its electrical power from thetermination power line of attached SCSI devices. If this powersupply is not available, the adapter switches automatically toreceive power from the USB bus.There are cases when the USB bus cannot supply the needed powerfor the USB2Xchange to operate—if, for example, you’re using anunpowered USB hub and the attached SCSI devices don’t supplySCSI termination power. In these cases, you may need to use anoptional DC power supply.Note: Adaptec strongly recommends that you plug theUSB2Xchange directly into a USB port on your computer. Ifyou must connect through a USB hub, use only a self-powered USB hub.You receive an error message (like the one shown below) if theUSB2Xchange is not supplied with enough power to operate.