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2 X 2 SCSI MATRIX SWITCH
5. Configuration and Operation
5.1 SCSI Cable Interface Requirements
The 2 x 2 SCSI Matrix Switch can be installed at any point on the SCSI bus. Always
use high-quality cables for optimum computer performance and reliability.
The SC121A differential switch contains 68-pin high-density connectors for up
to 80-MB-per-second wide Ultra SCSI and Ultra2 SCSI computers and peripherals.
The maximum cable distance should not exceed 82 ft. (25 m).
The SC120A-R2 single-ended/low-voltage differential switch contains 68-pin
high-density connectors for up to 160-MB-per-second wide Ultra SCSI, Ultra2 SCSI,
and Ultra160 SCSI computers and peripherals:
• Low-Voltage Differential (LVD):
When operating with LVD devices, the SC120A-R2 supports 160-MBps wide
Ultra160 SCSI computers and peripherals. The maximum cable distance for
LVD should not exceed 82 ft. (25 m) total length.
• Single-Ended (SE):
When operating with SE devices, the SC120A-R2 supports 40-MBps wide Ultra
SCSI computers and peripherals. The maximum cable distance for SE should
not exceed 20 ft. (6 m) total length.
Black Box offers standard and custom SCSI cables for connecting the SCSI
Switch to host devices and peripherals. Call Black Box Technical Support for
details.
5.2 Internal Terminator Selection
The SCSI Switch contains internal SCSI-bus terminators for each port.
Termination is required at both ends of a SCSI bus for proper operation. Each
port can have its internal terminator enabled or disabled from the front-panel
display and keypad.
Refer to Figure 5-4 to select internal termination.
NOTE
Data errors will result if more than two sets of terminators are installed
on any SCSI bus (see Figures 2-1 and 2-2).
