12
2 X 2 SCSI MATRIX SWITCH
2.3.2 G
ENERAL
H
ARDWARE
D
ESCRIPTION
The 2 x 2 SCSI Matrix Switch’s rear panel identifies each of the independent SCSI
ports. SCSI ports A and B have two daisychained connectors per port and SCSI
ports 1 and 2 have single connectors for installation of SCSI devices. You can install
the SCSI Switch at any point on the SCSI bus.
Each port has internal termination that can be turned on or off from the LCD
panel. External “terminator power” (TERMPWR) for devices and terminators are
provided by internal resettable fuses.
The SCSI Switch does not require a device ID and is completely transparent to
all computers and peripherals on the SCSI bus. No additional software is needed
for installation and operation. A universal switching power supply automatically
adapts to input voltages between 95 VAC and 260 VAC.
2.3.3 U
LTRA
2 SCSI C
OMPATIBILITY
The SCSI Switch supports Ultra2 SCSI, 80-MBps (wide) SCSI host adapters,
computers, and peripherals in asynchronous and synchronous mode. (SC120A-R2
also supports Ultra160 SCSI, 160-MBps devices.) The SCSI Switch conforms to
ANSI X3.131 and X3T9.2 specifications for single-ended devices. Disconnect and
reselect functions are fully supported to ensure complete SCSI compatibility.
2.3.4 SCSI S
WITCH
I
NSTALLATION
Ports A and B are fully bidirectional to ports 1 and 2 (see Figures 2-1 through 2-3).
You determine where to connect computers, host adapters, and peripherals. In
general, if daisychained ports are required for connection to external peripherals,
use ports A or B.
The LCD panel is used to select port connections and enable or disable each
internal SCSI port terminator. Refer to
Chapter 4
for complete instructions on
operating the LCD keypad.
You can selectively enable or disable any internal terminator to meet system
configurations and requirements.
NOTES
1. For proper operation of any SCSI bus, there must not be a “hanging”
line or cable. Termination should be enabled on active SCSI ports that
are not connected through to another port.
2. Connections can be made to either connector on the appropriate port.
3. In Figures 2-1 and 2-3, “Term” shows where terminators should be
installed.
