Seagate ST34573N/W/WD/LW/WC/LC manual Cable characteristics for single-ended I/O circuits

Models: ST34573N/W/WD/LW/WC/LC ST39173N/W/WD/LW/WC/LC

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Barracuda 9LP Installation Guide, Rev. E

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Figures 3a, 3b, 3c, and 3d show typical drive connections. The following tables list the maximum cable lengths and number of devices allowed on a daisy-chain cable for I/O data transfer rates shown.

Table 4a. Cable characteristics for single-ended I/O circuits

 

Maximum distance between

Number of attached SCSI

terminators (meters) [1] [3]

devices

Fast-5

Fast-10

Fast-20

Fast-40

 

 

 

 

 

1 to 4 maximum capacitance

 

 

 

 

(25 pF) SCSI devices

6

3

3

N/A

 

 

 

 

 

5 to 8 maximum capacitance

 

 

 

 

(25 pF) SCSI devices

6

3

1.5

N/A

 

 

 

 

 

9 to 16 maximum capacitance

 

 

 

 

(25 pF) SCSI devices

6

3

[2]

N/A

 

 

 

 

 

[1]For environments where all elements of the bus (cables, device inter- faces, environmental noise and other parameters) are controlled to be better than minimally required, it may be possible to extend the path length and device count.

[2]Extending the device count beyond eight requires specification con- trol beyond the minimum specified in the ANSI T10/1142D docu- ment. It is recommended that the devices be uniformly spaced between terminators with the end devices located as close as possi- ble to the terminators.

[3]Values specified by data rate shall apply even if a slower data rate is negotiated.

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Seagate ST34573N/W/WD/LW/WC/LC, ST39173N/W/WD/LW/WC/LC manual Cable characteristics for single-ended I/O circuits