Force Computers SPARC CPU-54, Справочное руководство

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Setting the SCSI Termination Installation
2 - 10 SPARC/CPU-54
Setting the SCSI Termination
The SPARC/CPU-54 provides two Ultra Wide SCSI buses. SCSI 1 is
accessible via the front panel and the backplane via the IOBP-54. SCSI 2
is available via the backplane via the IOBP-54. The SPARC/CPU-54
enables and disables the SCSI termination automatically according to
the board’s position in the SCSI bus, if switch SW5 is set to the respec-
tive default settings.
SCSI 1 Termination
The SCSI 1 bus is available via the front panel connector and via the
VMEbus P2 connector and the IOBP-54. By default, switch SW5-2 is set
to OFF and switch SW5-3 is set to ON to enable automatic termination
of the SCSI bus 1. To guarantee proper termination, leave switches in
the mentioned position.
Caution
Only connect the SCSI cable at its end connectors and never at its
middle connectors. Otherwise, data may be lost.
SCSI 2 Termination
Caution
If you use a flat ribbon T-cable at the SCSI 2 bus, the termination of
SCSI 2 has to be set manually to prevent data transmission errors.
Before installing the board, check Figure 5 “SCSI Termination Con-
cept of SPARC/CPU-54 and IOBP-54” on page 2-11 whether this
applies to your planned configuration.
The SCSI 2 bus is only available via the VMEbus P2 connector and can
only be terminated manually. The following options apply:
• The SCSI 2 connector on the IOBP is connected to SCSI devices.
The switch SW5-4 must be set to the OFF position which enables the
termination on the CPU board.
• The SCSI 2 connector on the IOBP is connected to SCSI devices, but a
flat ribbon T-cable is used. The switch SW5-4 must be set to the ON
position which disables the termination on the CPU board.