LSI 320 - Manual (Page 27)

Terminating the SCSI Bus 2-11
Copyright © 2002 by LSI Logic Corporation. All rights reserved.
2.4 Terminating the SCSI Bus
The SCSI bus contains all the devices that you connect with SCSI
cables. When you connect the first and last physical SCSI devices on the
ends of the SCSI bus, you must have termination active. You must
remove or disable termination on all other SCSI devices on the same
bus.
If you connected only internal SCSI devices on a bus, the host adapter
automatically terminates itself. If you connected only external SCSI
devices on a bus, the host adapter also terminates automatically.
Automatic termination occurs because the host adapter connection is at
the end of the SCSI bus. If you connect both internal and external SCSI
devices on a bus, the host adapter automatically disables its termination.
This occurs because the host adapter is in the middle of the SCSI bus.
2.4.1 LSI20320 Host Adapter Termination
The LSI20320, LSI20320H, LSI20320L, and LSI20320-R host adapters
provide active termination with an automatic means of enabling and
disabling the termination. When you connect SCSI devices to both the
internal and external connectors, host adapter termination is
automatically disabled.
2.4.2 LSI21320 Host Adapter Termination
The LSI21320(-R) host adapter provides active termination with an
automatic means of enabling and disabling the termination. When you
connect SCSI devices to the internal and external connectors on
Channel A, termination for Channel A is automatically disabled.
Channel B has only one SCSI connector. Channel B termination is
always enabled.
2.4.3 LSI22320 Host Adapter Termination
The LSI22320(-R) host adapter provides active termination with an
automatic means of enabling and disabling the termination. When you
connect SCSI devices to both the internal and external connectors on a
given channel, termination for that channel is automatically disabled.