HP 9000 Series Service Manual

11-8 Chapter 11
SCSI Peripherals and I/O Information
Termination/Term Power
1. The SCSI bus requires termination at both ends of the bus. The host adapters generally supply on
board terminators and should be located at one end of the bus. The multifunction I/O host bus
adapters are the current exception since they are designed to reside in the middle of the SCSI bus.
Therefore, buses associated to these multifunction I/O adapters are terminated on the two ends of
the associated internal and external buses. Since an external connection may not be present, insure
that the ACTIVE terminators supplied with the product are installed on the external connection at
the back of the system.
2. When possible, put devices that supply termination power at both ends of the bus. The host
adapters will always supply termination power which is required for proper bus operation.
However, noise immunity can be improved by placing another source of termination power at the
other end of the bus. Most peripheral devices are optionally capable of supply termination power.
(See the appropriate peripheral descriptions in this section.)
Termination Characteristics and Power
Terminator power - Will be supplied by the Initiators and may be supplied by any or all connected
devices. HP recommends that terminator power be supplied by the Host Bus Adapter (HBA) Initiator
and the last device on the SCSI Bus to help decrease interface error rates and provide better balance to
the TERMPWR contacts. Recommended current limiting is 1.5 amps. with a maximum of 5 amps.
(The limiting device may be fused or resetable.)
Single-Ended
TERMPWR = 4.25 to 5.25 vdc. with 900 ma source drive capability for the 50-pin Cable, and 1500
ma source drive capability for the 68-pin cable.
+MSG 25 49 50 59 -MSG
+SEL26515260-SEL
+C/D 27 53 54 61 -C/D
+REQ 28 55 56 62 -REQ
+I/O 29 57 58 63 -I/O
Ground 30 59 60 64 Ground
+DB(8) 31 61 62 65 -DB(8)
+DB(9) 32 63 64 66 -DB(9)
+DB(10) 33 65 66 67 -DB(10)
+DB(11) 34 67 68 68 -DB(11)
Signal Name
Connector
Contact
Number
Cable
Conductor
Number
Cable
Conductor
Number
Connector
Contact
Number
Signal Name

HP 9000 Series Specifications

General

Brand	HP
Model	9000 Series
Category	Server
Language	English