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AHA-3940AU/AUW Installation Guide
Part Number: 511418-00, Rev. A
Print Spec Number: 496346-00
Current Date: 3/12/97
ECN Date:3/10/97
Connecting SCSI Devices
Caution:
AHA-3940AU/AUW host adapters
support only single-ended SCSI devices. Do
not connect differential SCSI devices, because
they may damage the host adapter. Read the
SCSI device documentation if you are not
sure whether the device is single-ended or
differential.
Connecting Cables
SCSI devices are cabled together in a single,
connected series called the SCSI bus. SCSI cables
must run sequentially from one device to the next,
with no branching.
1
Lay out the cables and find the pin-1 element of
each cable and device connector.
On internal cables, pin 1 is usually marked with a
contrasting color on one edge of the ribbon cable,
and a small triangle or number 1 marks pin 1 on
the SCSI connector. External cables can only be
plugged in one way, so pin-1 orientation is
automatic.
2
Attach the SCSI cable(s) to the host adapter and
the device(s), using the internal and/or external
connector(s). Be sure to maintain correct pin-1 ori-
entation throughout the bus for each channel. If
you are connecting 8-bit SCSI devices to
Channel A of an AHA-3940AUW, you may use
the internal 50-pin connector. If you must connect
8-bit SCSI devices to Channel B you will need
68-pin-to-50-pin converters. Refer to the User’s
Guide for detailed information or Adaptec’s
homepage under Cables.
On the AHA-3940AU host adapter, SCSI Channel
A has one internal 50-pin connector J1. Channel B
has one external J2 and one internal 50-pin con-
nector J6. The AHA-3940AUW Channel A has
one internal 68-pin connector J1, one internal
50-pin connector J4. Channel B has one internal
68-pin J2 and one external 68-pin connector J5.
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