Adaptec AVA-1505 Installation Guide - Page 4

5 Connecting Peripherals Setting SCSI IDs You must assign a different SCSI ID to each device on the AVA-1505 SCSI bus. See your SCSI peripheral documentation for directions on how to determine the ID and change it. The default SCSI ID for AVA-1505 host adapters is SCSI ID 7. Connecting Cables SCSI devices are cabled together in a single, connected series called the SCSI bus. The SCSI bus cables must run sequentially from one device to the next. The host adapter is at the end of the SCSI bus if either the internal or the external SCSI connector is unused. The host adapter is in the middle of the bus if internal and external SCSI devices are installed. Caution: AVA-1505 host adapters support only single-ended SCSI devices. Differential SCSI devices may be damaged if connected to the host adapter. The peripheral documentation will tell you whether the device is single-ended or differential. 1 Lay out the cables and find the pin-1 element of each cable and peripheral connector. On internal cables, pin 1 is usually marked with a contrasting color on one edge of the ribbon cable, and a small triangle marks pin 1 on the SCSI connector. External cable connectors can only be plugged-in one way, so pin-1 orientation is automatic. 2 Attach the SCSI cable(s) to the host adapter and the peripheral(s), using the internal and/or external connector(s). 3 Be sure to maintain correct pin-1 orientation throughout the bus. The AVA-1505 uses a 25-pin DB25 external connector (Apple compatible), and a 50-pin flat ribbon-type internal connector. Terminating the SCSI Bus Cable The last physical SCSI device on either end of the SCSI bus must have a set of resistors called termina- 3