3.3Cabling SCSI Devices

The cable provided in your host adapter kit is matched to the host adapter board and its operation. The Ultra160 SCSI cable also has built-in multimode (LVD/SE) termination because most Ultra160 hard disk drives are not made with on-board LVD termination.

Table 3.3 lists standard cable specifications.

Table 3.3

Cable Specifications

 

 

 

 

 

 

 

 

 

Maximum Bus Length, Meters1

 

 

 

 

 

 

STA Term

 

SE

 

LVD

Maximum Devices

 

 

 

 

 

 

Ultra SCSI

 

1.5

 

see note2

8/4

 

 

 

 

 

Wide Ultra SCSI

1.5/3

 

see note2

8/4

 

 

 

 

 

 

Ultra2 SCSI

 

see note3

 

12

8

Wide Ultra2 SCSI

see note3

 

12

16

 

 

 

 

 

 

Ultra160

 

see note3

 

12

16

1.This parameter may be exceeded in point-to-point and engineered applications.

2.LVD was not defined in the original SCSI standards for this speed. If all devices on the bus support LVD, then 12-meter operation is possible at this speed. However, if any device on the bus is SE only, then the entire bus switches to SE mode, and the distances in the SE column apply.

3.SE and High Voltage Differential (HVD) are not defined at greater than Ultra speeds.

3.3.1Internal SCSI Cables

You can make internal SCSI bus connections to your Ultra160 SCSI host adapter with an unshielded, 68- or 50-conductor ribbon cable. Some internal cables come with an LVD/SE terminator on one end. This end must be farthest from the host adapter. Figures 3.8 through 3.10 provide examples of internal cables.

3-10

Ultra160 SCSI to PCI Host Adapter Characteristics