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SCSI SWITCH II
4. Operation
The SCSI Switch II begins operating as soon as it has been connected to a
working power source through its power supply; it has no On/Off switch.
(The Switch is in no danger if power is removed or goes down, but data may
be lost if this happens while the SCSI system is operating.)
The main SCSI bus is always connected to one of the three branch buses.
You control which of the branch buses is connected by pressing the
pushbuttons (labeled Ports A, B, and C) on the SCSI Switch II’s front panel.
When you select a new branch, the SCSI Switch II waits to connect to the new
branch until it is safe to disconnect from the old branch (data transmission to
and from the old branch has stopped).
Once you’ve plugged in the switch, all of the LEDs will light for one second
to signal a successful reset. The LED for the last branch connected will light
up. If it blinks rapidly, it’s transmitting data. If it stays constantly lit, there is
no data currently transmitting.
To switch branches, push the button labeled Port A, Port B, or Port C. If
a previous connection is still active (noted by a rapidly flickering port LED),
the Switch will flash the LED of the port you selected (approximately once
per second) until the bus currently transmitting is inactive for 8 seconds.
Then that branch is disconnected, and the branch you selected is connected.
The LED next to the branch you selected should be lit, and the LED of the
disconnected port should not be lit.
When power is restored to the SCSI Switch II after the power fails or the
Switch’s power is unplugged, the Switch will connect the main bus to the
branch bus last selected. If power is lost during a pending branch change, the
previous connection (the one that was still active when power was lost) is not
re-established unless you push the button for that branch’s position.
