Fujitsu M2266S Technical Handbook page 43

The maximum length of the SCSI cable is as follows. If more than one SCSI
device is connected, the total cable length must not exceed the following:
• 6 m for single-ended type SCSI
• 25 m for differential type SCSI
The use of a 25-pair twisted cable satisfying the following requirements is
recommended.
Single-Ended Type
Conductor Size: 28 AWG (American Wire Guage) or bigger
Characteristics impedance: 100 to 132
Differential Type
Conductor Size: 28 AWG or bigger
Characteristic impedance: 100 to 122 0
Each pair of wires in the 25-pair twisted cable must be connected to pins n
and n+1 (where n is an odd number) on the interface connector. Cables
having an identical impedance must be used on the same SCSI bus to reduce
signal reflection and maintain transmission characteristics.
When an SCSI device is connected to the SCSI cable (except at either end of
the cable), connection to the SCSI connector must be at a branch point of the
cable. If an SCSI device is connected to one end of the SCSI bus, no cable
should be connected after the last SCSI device, except when the cable has a
terminating resistor. (See Figure 2.20.)
M2266S/H
Technical Handbook
2-18 F5810125-01 . . . A Fujitsu America, Inc.