Terminating The Scsi Bus - Adaptec AHA-3980 User Manual

AHA-3980/3980W/3985/3985W User's Guide
Note:
The computer in which the AHA-398x is installed can
share external SCSI devices with another computer. For
more information, see Sharing SCSI Devices with a Second
Computer on page 5-18.

Terminating the SCSI Bus

SCSI bus terminators must be either installed in, or enabled on, the
first and last SCSI devices on each AHA-398x channel; otherwise,
the devices will not operate properly. Terminators on all other
devices must be removed or disabled.
AHA-398x termination is enabled by default on all adapter channels.
At the other end of the SCSI bus, termination is usually provided by
the passthrough terminator (for the internal channels) or an external
SCSI device (if devices are attached to the external connector of
Channel A).
The following sections describe termination for each of the channels.
In reading the instructions, note that termination on most SCSI disk
drives, CD-ROM drives, and other SCSI devices is controlled by a
jumper or switch close to the SCSI connector. Some SCSI devices
have a resistor module that you insert or remove to control termina-
tion. See your device documentation for details.
Note:
Some SCSI disk drives allow their terminators to
receive termination power from the SCSI bus instead of
from the drive's power supply. AHA-398x RAID adapters
support this option, because they always supply termina-
tion power on the SCSI bus.
5-12
AHA-3980/3980W/3985/3985W User's Guide
Stock Number: 510810-00, Rev. D
Print Spec Number: 493479-00
Current Date: 3/1/99
Page: 5-12
ECN Date: 3/19/96