Nikon LS-10E instruction manual Terminating the Scsi Chain

[a]

t~~

f

[b)

Fig. 3.8 SCSI termination network used with the LS-10 scanner

Terminaison interne du LS-10

SCSI-AbschluB an Scanner LS-10

[c)

[d)	[e)
Fig. 3.9 SCSI internal flat cable
Cable en nappe SCSI interne
Internes SCSI-Flachkabel

3-4 Terminating the SCSI Chain

The SCSI chain is an electrical bus connecting two or more devices. It is critical that this bus be correctly terminated for the SCSI peripherals to work properly.

Termination is an electronics term that applies to the impedance found at both ends of the bus. The electrical signals on the SCSI bus are changing rapidly between their digital " on " and "off" states . To minimize nOise, a termination is placed on each end of the bus. The effects of this termination may be subtle, but are critical.

Typically, the computer sits at one end of the SCSI bus. Assuming this is the case, the SCSI controller in the computer has to be terminated .

Warnlngl

Incorrect SCSI termination can cau.e unpredictable error•.

If one other SCSI peripheral shares this SCSI bus, it also has to be terminated. If additional SCSI devices sit on the bus between the two end SCSI devices, these devices can NOT be terminated . Only two terminated devices can reside on the SCSI bus, one at each end .

Improperly terminated SCSI peripherals can fail immediately or may work correctly for a week before generating their first errors.

Terminating an LS-10

The internal-mount LS-10 scanner uses a set of termination networks as seen in Figure 3.8. The pins of these term ination networks are numbered beginning with number one. The number one pin is indicated with a black dot.

[a]SCSI termination off

[b)SCSI termination on

3-5 SCSI Cables Used with Internal Scanners

The internal SCSI cable is a 50-pin flat cable with two identical stamped connectors on each end . One end of this cable will connect to the SCSI controller while the other end will connect to the connector on the rear of the LS-10 scanner. A typical SCSI internal cable is seen in Figure 3.9.

[c)SCSI flat cable

[d)SCSI 50-pin connectors

[e)Connector protection key

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