Installing the A5150A Adapter

SCSI Bus Termination

Table 2-3

Auto Termination PDC Versions

 

 

 

 

HP 9000 System

PDC Version

 

 

 

 

A400 and A500

40.20 or later

 

 

 

 

L-Class

39.40 or later

 

 

 

 

N-Class

39.41 or later

 

 

 

The A5150A is supported on the A400, A500, L-Class, and N-Class

HP 9000 systems.

Bus Termination

The SCSI bus must be properly terminated. The first and last physical SCSI devices on the ends of the SCSI bus must be terminated either by physical terminators or auto termination. The terminators of all other SCSI devices on the bus must be removed or disabled. Note that the A5150A HBA is also on the bus. However, because the A5150A HBA contains an automatic termination feature, external terminators on the HBA are not usually required. (Terminators are not shipped with the A5150A; you can order them separately, if needed.) The A5150A provides automatic termination when a SCSI cable from a powered SCSI device (a peripheral or other HBA) is connected to either the internal or external connector of the A5150A. Some exceptions where external terminators are required are described in “When and How to Turn Off Auto Termination” on page 31.

The older A5150A HBA (A5150-60001) has two sets of pins that control enabling and disabling (defeating) the auto termination feature. The pins—labeled A_TERM and B_TERM—are at the end of the HBA that is opposite the bulkhead connectors. A_TERM controls the auto termination feature for channel A, and B_TERM controls the feature for channel B.

NOTE

The A5150A’s auto termination feature cannot be set independently for

 

the internal and external connectors of the HBA.

 

 

30

Chapter 2