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SCSI Bus Signal Converters

6.2 Installing SCSI Bus Signal Converters

Table 6–1 lists the maximum bus lengths using the end-bus conﬁguration for all

DWZZAs.

Table 6–1 StorageWorks SCSI Buses

SCSI Bus DWZZAs SCSI Bus Length Cable

Type MB/s –VA –AA SBB Shelf† Cable–Host‡ Maximum§ Type Order No.

No SCSI Bus Signal Converters

Fast 10 0 0 0.9 m ( 3.0 ft) 2.1 m ( 6.9 ft) 3 m ( 9.8 ft) SE BC09D, BN21H

Slow 5 0 0 0.9 m ( 3.0 ft) 5.1 m (16.7 ft) 6 m ( 19.7 ft) SE BC09D, BN21H

Differential SCSI Host

One SCSI Bus Signal Converter

Fast 10 1 0 3 m ( 9.8 ft) 23 (75.5 ft) 26 m ( 85.3 ft) DF BN21K, BN21L

Slow 5 1 0 6 m (19.7 ft) 23 (75.5 ft) 29 m ( 95.1 ft) DF BN21K, BN21L

Single-Ended SCSI Host

Two SCSI Bus Signal Converters

Fast 10 1 1 3 m ( 9.8 ft) 26 m ( 85.3 ft) 29 m ( 95.1 ft) SE

BC09D, BN21H

BN21K, BN21L

Slow 5 1 1 6 m (19.7 ft) 29 m ( 95.1 ft) 35 m (114.8 ft) SE

BC09D, BN21H

BN21K, BN21L

Legend:

†—First shelf input connector to last shelf terminator.

‡—Host terminator to SBB shelf input connector or SBB shelf DWZZA–VA input connector.

§—Host terminator to SBB shelf terminator.

SE—SCSI–A SCSI cable, 50-conductor.

DF—SCSI–P SCSI cable, 68-conductor.

In the end-bus conﬁguration, all the cables are terminated in the converter as

well as at the host and the SBB shelf. Note that this conﬁguration effectively

starts a new bus at each connection.

For example, when using a single-ended and no converters, the maximum

length of the single-ended SCSI bus from the host terminator to the SBB shelf

terminator is 6 meters (19.7 ft). By using two converters, the maximum distance

from the host terminator to the SBB shelf terminator would theoretically be 37

meters (121.4 feet). However, the actual maximum length when using approved

cables is as shown in Table 6–1.

• The maximum bus length from the host terminator to the desktop converter

50-pin connector can be either 3 meters (9.8 ft) or 6 meters (19.7 ft) depending

upon the bus speed.

• The maximum cable length from desktop converter 68-pin connector to the

SBB shelf converter 68-pin connector is 23 meters (75.5 ft).

• The maximum bus length from the SBB shelf converter backplane connector

to the shelf terminator can be either 3 meters (9.8 ft) or 6 meters (19.7 ft)

depending upon the bus speed.

6–4 SCSI Bus Signal Converters

1 2 ... 51 52 53 54 55 56 57 58 59 60 61 ... 73 74

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Digital Equipment Corporation Storage Works Guía de usuario Pagina 56

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