Terminating The Scsi Bus; Termination With Internal Devices Only - Adaptec AMM-1510M User Manual

AMM-1525M/1510M/525M User's Guide

Terminating the SCSI Bus

To reduce signal reflections on the SCSI bus, the first and last physi-
cal SCSI devices (including the host adapter) must have a set of
resistors called terminators either installed or enabled. If the termina-
tors on the first and last SCSI device are not installed or enabled, the
signal may echo when it reaches the end of the cable; that echo often
seems like a real signal to the SCSI device.
1
Identify which two SCSI devices form the physical endpoints
of your SCSI bus, then terminate these devices.
2
Remove or disable termination on all other SCSI devices
installed between the ends of the SCSI bus.
– Some SCSI devices use a jumper or a switch located close to
their SCSI connector(s) to control termination. On other
SCSI devices, you must physically remove or install termi-
nator resistor module(s). Refer to the device's documenta-
tion to determine how to enable or disable termination on
your particular SCSI device.
– Since only internal SCSI devices can be connected, the
AMM-1525M/1510M is always situated at the end of the
SCSI bus; SCSI termination on the adapter is always
enabled and cannot be changed.
Termination
Enabled
No
Termination
Figure 2-7. Termination With Internal Devices Only
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