User`s guide

DLT MiniLibrary (TL891) - User’s Guide
B-12 EK-TL891-UG. A01
B.3 Interface Cable Specifications
The detailed requirements for SCSI cables are set forth in ANSI X3.131-1994. It
is recommended that all SCSI cables used with the DLT MiniLibrary Base
Module meet at least the following requirements:
•
Shielded or double-shielded, as required to meet EMI specifications
•
Impedance match with cable terminators of 132 ohms, ideally
•
Characteristic impedance between 90 and 132 ohms, required
•
50-conductor flat cable or 25-pair twisted-pair should be used
•
The maximum cable length for a single-ended SCSI bus is 19.68 feet (6 m)*
•
The maximum cable length for the entire differential SCSI bus is 82 ft. (20
m)*
•
Cables of different impedances should not be used together
* When calculating the overall length of the bus, be sure to include the internal
cabling of the module, which is 75 inches (190 cm) in the daisy-chained option.
In the independent-bus version, the lengths are 19 inches (48 cm) for drive 1. 25
inches (64 cm) for drive 2, and 33 inches (84 cm) for the robotics in the
separately-wired option. The total internal wiring length of the separately-wired
version is 77 inches (195 cm).
Additional specifications to assure the highest SCSI performance can be found in
ANSI X3.131-1994 or later.
NOTE
This equipment has been tested for
electromagnetic emissions and immunity using
good quality shielded cables. The use of
unshielded cables, poor quality cables or other
variances from good practice may result in non-
compliance with national and international rules.
B.3.1 Terminators
A terminator must be installed on the drive if the drive is to be used at either end
of a SCSI bus, such as the first or last device along a daisy-chain, or as a single
SCSI peripheral. The appropriate type and quantity of terminator is shipped with
your module. It is packaged in the accessory bag that arrives with the module.