5
AHA-1530P/1532P Installation Guide
Part Number: 510484-00, Rev. B
Print Spec Number: 492211-00
Current Date: 4/27/94
ECN Date: 5/3/94
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If you need to set SCSI IDs with switches or jumpers,
we recommend that you assign SCSI IDs 0 and 1 to
the first two SCSI hard disk drives.
Terminating SCSI Devices
The SCSI bus is the cabling that connects SCSI
devices to the AHA-1530P/1532P. Data can only be
transmitted on the SCSI bus if the devices at each end
of the bus are terminated. Termination must be dis-
abled on all other devices on the SCSI bus.
Termination on the host adapter itself is controlled
by software commands via the SCSISelect utility. The
default setting is Automatic, which works like this:
■
The host adapter terminates itself if only external
or only internal peripherals are connected to it
(that is, if the host adapter is the last device on the
bus).
■
The host adapter disables its termination if both
internal and external peripherals are connected to
it (that is, if the host adapter is in the middle of
the bus).
You can also change the host adapter termination
setting to Enabled or Disabled. To do this, first com-
plete the physical installation, then run SCSISelect.
(See Section 6, Configuring the Host Adapter.)
Termination Status Indicator
The onboard LED next to the internal SCSI connector
changes color to indicate the SCSI bus termination
status:
■
A green light means that termination is set cor-
rectly (two devices are terminated).
■
A red light means that more than two devices are
terminated.
■
An orange light means that fewer than two devices
are terminated.
(The LED lights up only when the disk drive is
active.)
