Adaptec 39160 User Reference - Page 10

Adaptec SCSI Card 39160 User's Reference Terminating the SCSI Bus To ensure reliable communication on the SCSI bus, the ends of the SCSI bus must be properly terminated. This is accomplished when the device at the end of each cable, or the end of the cable itself, has a terminator installed (or enabled). Terminators must be removed, or termination must be disabled, on devices between the ends of each cable. Since the method for terminating a SCSI device can vary widely, refer to the device's documentation for instructions on how to enable or disable termination. Here are some general guidelines for termination: s Internal Ultra160 and Ultra2 SCSI devices come from the factory with termination disabled and cannot be changed. Proper termination for these internal devices is provided by the builtin terminator at the end of the 68-pin internal LVD SCSI cable. s Termination on Wide SCSI, Narrow SCSI, and Ultra SCSI devices usually is controlled by manually setting a jumper or a switch on the device, or by physically removing or installing one or more resistor modules on the device. s Termination on most external SCSI devices is controlled by installing or removing a SCSI terminator. However, termination on some external SCSI devices is enabled or disabled by setting a switch on the back of the SCSI device. s By default, termination on the Adaptec SCSI Card 39160 itself is set to Automatic (the preferred method). We recommend that you do not change this default setting. 4