Toshiba Magnia 560S - Manual (Page 104)

Troubleshooting 86
Troubleshooting
Table 7.5 Other Potential Problems (Continued)
Topic Information
SCSI bus requirements The ANSI specification dictates the following:
The maximum signal path length between terminators is
3 meters when using up to 4 maximum capacitance
(25 pF) devices and 1.5 meters when using more than 4
devices.
SCSI devices should be uniformly spaced between
terminators, with the end devices located as close as
possible to the terminators.
The characteristic impedance of the cable should be 90
+/- 6 ohms for the /REQ and /ACK signals and 90 +/- 10
ohms for all other signals.
The stub length(the distance from the controller's
external connector to the mainline SCSI bus) shall not
exceed 0.1m (approximately 4 inches).
The spacing of devices on the mainline SCSI bus should
be at least three times the stub length.
All signal lines shall be terminated once at both ends of
the bus powered by the TERMPWR line.