2-9
Getting Started
AHA-2740W/2742W/2744W User’s Guide
Stock Number: 510647-00, Rev. A
Page: 2-9
Print Spec Number: 492897-00
Current Date: 8/3/94
ECN Date: 8/9/94
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Termination on the SCSI Bus
To reduce signal reflections on the SCSI bus, the device connected at
the end of each SCSI connector must have a set of resistors called ter-
minators either installed or enabled. All other SCSI devices installed
between the last device and the host adapter must have their termi-
nators either removed or disabled. In addition, termination on the
host adapter itself must be properly configured.
Most SCSI devices use a jumper or a switch located close to their
SCSI connector(s) to control termination. On some SCSI devices, you
will have to physically remove resistor module(s). Refer to the man-
ufacturer’s documentation to determine how to enable or disable
termination on your particular SCSI device(s).
Note:
When terminating differential drives, the hard drive
should be in the middle of the SCSI bus because most differ-
ential drives do not have termination jumpers. Termination
must be enabled on the host adapter and at the end of the
cable by a cable terminator.
Note:
Some drives allow for the option of supplying
termination power to their resistor modules from the SCSI
bus instead of from the drives power supply. This option is
acceptable since the AHA-2740W/2742W/2744W always
supplies termination power on the SCSI bus.
