Cabling
Requirements
The
disk drive adheres to
the
cabling requirements and limitations
set
forth in
the
ANSI SCSI
specifications. Refer
to
the
SCSI specifications for additional details.
• Cables with a characteristic impedance of 100 ohms
±1O%
are recommended for unshielded
flat
or
twisted
pair
ribbon cable.
• Cables with a characteristic impedance of
90
ohms ±10% are preferred for shielded cables.
• To minimize discontinuities and signal reflections, do not use cables with different
impedances on
the
same bus.
• A minimum wire size of
28
AWG should be used
to
minimize noise effects and ensure proper
distribution of termination power. Note: because
of
physical size limitations of current
connector designs,
a wire size
of
30 AWG should be used for wide differential cabling.
• Cables must be properly terminated.
Single-ended Cable
• A 50-conductor flat cable or 25-signal twisted-pair cable should be used. Cable length
should be equal
to
or
less
than
6.0 meters. This refers
to
internal and external cable length
(except stubs).
• A
stub
length of no more
than
0.1
meter is allowed off
the
main line interconnection within
any connected device.
Differential Cable
• For narrow differential drives, a 50-conductor flat cable
or
25-signal twisted-pair cable
should be used. For wide differential drives,
a 68-conductor flat cable
or
34-signal twisted
pair cable should be used. Twisted
pair
cabling
is
preferred
to
minimize noise. Cable length
should be equal to or less
than
25
meters. This refers to internal and external cable length
(except stubs).
• A
stub
length
of
no more
than
0.2 meter is allowed off
the
main line interconnection within
any connected device.
2-10 Product Installation
DRAFT
1/18/93 09:58
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