Configuring the SCSI Bus
Some basic SCSI principles must be applied in order to configure the SCSI
bus on your system correctly. These are:
The SCSI bus must be terminated at both ends, and only at the ends.
Configure the termination on your VAX-SCSI adapter using the
configuration information in the preceding chapter. Refer to the
documentation for each device on the SCSI bus, to ensure:
1. Devices at the ENDS of the bus have TERMINATION
2. Devices not at the END of the bus have TERMINATION
Note: Most difficulties with the SCSI bus can be traced to improper
termination and cabling.
Note: Your Compaq VAX™-SCSI card always provides High Voltage
Differential Termination (HVD). You must provide HVD
termination after the last device on the end of the external cable.
Each device and host adapter on the SCSI bus must have a unique SCSI ID.
The host adapter must be left at its default ID of 7.
On a 16 bit (WIDE) VAX™-SCSI bus, each device must have a unique SCSI
ID from 0 - 7. The Compaq VAX™-SCSI adapter defaults to ID 7. All other
devices on the bus should be given IDs from 0 – 6. Refer to the
documentation for each of your devices for the method of setting the SCSI ID
for that device.
NOTE: VAX™-OpenVMS™ does not currently support SCSI IDs above 7.
Refer to your specific operating system for details.