2. HARDWARE SETUP
DC-395 Series User’s Manual
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9
2.4 Checking the Terminators on the SCSI Bus
In order to stabilize the SCSI bus, only two sets of terminators can be installed - one at each
end of the SCSI bus. The DC-395 series is equipped with
Active Terminators
that
automatically switch from Enabled to Disabled or vice versa by scanning the devices
connected on the SCSI bus. So, manual termination adjustment is not required. The following
explains the terminator configuration of other devices on the SCSI bus:
1.
When only internal devices are connected to the DC-395 series adapter
: Leave the
terminator mounted on the last device only, with the SCSI card being the first SCSI
device. Remove terminators on all other devices connected in between.
2.
When only external devices are connected to the DC-395
series adapter
: Leave the
terminators mounted on the last device only. Since external SCSI devices are daisy
chained, this would be the device without another SCSI cable plugged into it. Remove
terminators on all other devices connected in between.
3.
When both internal and external devices are connected to the DC-395 series adapter
:
Leave only the terminators mounted on the last internal device and the last external
device. As in the above case, remove the terminators from all other devices connected in
between.
Note1:
For DC-395UW/F only
: When both Narrow (8-bit) and Wide (16-bit) devices are
connected to the Wide SCSI connector (either Internal or External), arrange the
devices so that a Wide device with termination enabled is at the end of the bus. A
Narrow device at the end of the bus can have termination problems in this case,
since the Wide bus is 16-bit and the terminator on the Narrow device is only
effective for the lower 8-bit (not the whole 16-bit).
Note2
: There are two types of termination available on SCSI devices, active and passive.
Active termination is strongly recommended to ensure system integrity, particularly
when devices with high transfer rates are being used. A SCSI CD-ROM drive
usually comes with a passive terminator. For proper termination, it is recommended
that you keep this terminator disabled, i.e.
avoid connect the CD-ROM drive at the
end of the SCSI bus
