ICP RS Series, User Manual, Page: 41 / 193

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The minimum distance between two connectors of a SCSI cable is 20 cm.
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Avoid cable stubs. If this is not possible, keep the stub length below 5 cm.
“Star cabling” are not allowed.
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Keep the number of transitions from flat to round cables and vice versa as small as pos-
sible. It is usually best to use flat or round cables, only.
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Check these points when routing SCSI cables:
- Avoid kinks in the SCSI cable
- Do not roll the SCSI cable up on itself
- Avoid routing the cable next to other cables
- Avoid routing the cable in the vicinity of noise sources such as power supplies
- Avoid routing the cable over sharp edges and in areas where it could get caught up
- Avoid routing/sticking the cable directly onto metal surfaces
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When using internal Wide/Ultra2 and Ultra160 SCSI cables make sure that the cable has
in both modes, SE and LVD, the correct impedance. The "Spectra Strip" cable material
from Amphenol fulfills the required specification (color coding: first pair blue/white all
other pairs orange/white) and complies with the ANSI T10/1142 D document. ICP vortex
offers a finished cable assembly which is based on this raw material (Order No.: 8839).
The cable has twisted cable pairs.
For external Wide/Ultra2 and Ultra160 SCSI round cables the same rules and specifica-
tions apply. ICP vortex offers here three cables: 8844, 8877 and 8880.
When making home-made SCSI cables, make sure that the insulation displacement con-
nectors are properly aligned and firmly pressed into the flat ribbon cable. Otherwise, the
whole cable might turn out to be a big short-circuit. Furthermore, check carefully that PIN 1
of the cable connects to PIN 1 of the connectors. A simple short-circuit and continuity test
before running the devices helps you to save time and money.
The same warnings as for home-made cables apply when you buy non-brand cables. If you
plan to run Fast-20 (Ultra) or Fast-40/80 (Ultra2 or Ultra160) devices, you should explicitly
ask your dealer if these cables are appropriate for the desired mode. (Note: The ICP product
range also includes some high quality SCSI accessories. Please see section B.4.4 of this
User's Manual or check our Website: http://www.icp-vortex.com, for further details).