Determining Cable Needs; External Cable Connectors; External Cable Lengths; Internal Cable Connectors - IBM PCI Dual Channel Ultra3 SCSI Adapter Installation And Using Manual

Determining Cable Needs

Use this section to determine your cable needs.

External Cable Connectors

External SCSI devices are manufactured with a variety of connectors. Ensure that you
have cables with the correct connectors for each external 8- or 16-bit device in your
planned SCSI chain.
LVD subsystems come with a cable having a VHDCI connector to attach to the
adapter's VHDCI connector.
For either external 8- or 16-bit single-ended devices, the cable end going to the adapter
is a 68-position high-density plastic D-shell connector. This connector joins to a VHDCI
to P-shell converter cable, which plugs into the adapter.

External Cable Lengths

SCSI specifications limit the total cable length attached as a function of SCSI bus
speed as follows:
v To attach an LVD subsystem running at Ultra2 (80 MB/s) or Ultra3 speed (160 MB/s),
the maximum cable length is 25 meters (approximately 80 feet).
v To attach an Ultra, 20 MHz synchronous device (such as a 16-bit SCSI disk drive
that can transfer up to 40 MB/s of data), the maximum cable length is 3 meters
(approximately 10 feet). Up to two devices can be attached.
v To attach a fast, 10 MHz synchronous device (such as an 8-bit SCSI disk that can
transfer up to 10 MB/s of data or a 16-bit SCSI disk that can transfer up to 20 MB/s
of data), the maximum cable length is 3 meters (approximately 10 feet). Up to four
devices can be attached.
For information about connecting SCSI devices to your adapter, see Appendix C,
"Connecting SCSI Devices to the Adapter" on page 25.

Internal Cable Connectors

Depending on your machine type, up to six (6) SCSI devices can be plugged into a
backplane. A 16-bit cable attaches the adapter's internal connector Channel B (J4) or
Channel A (J6) to the backplane. For an illustration of the SCSI connectors, see the PCI
Dual Channel Ultra3 SCSI Adapter on page 2.
To use internal SCSI devices in your system, obtain the necessary cables for your
system unit. Terminators are built onto the backplane within your system unit.
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Installation and Using Guide