SCSI Bus Terminators (Optional)
For those drives having the Active
Termination feature, this function can
be enabled by installing a jumper
between pins 13 and 14 of the Front
Option Jumper Block or connecting pins
9 and 10 of the Auxiliary Connector on
68 SCSI pin models. The using system
is responsible for making sure that all
required signals are terminated at both
ends of the cable.
80 pin SCA models do not have internal
SCSI bus terminators.
Some external terminator possibilities
for single-ended cabled systems are
listed below:
50 Pin Model
68 Pin Model
Terminators
Terminators
Data Mate
Data Mate
DM2000-02-R
DM2050-02-68S
DM500-06-R
DM2050-02-68R
Single-ended SCSI Terminators
Differential models do not have internal
SCSI bus terminators. Some terminator
possibilities are shown below:
68 Pin Model Terminators
Data Mate DM2050-01-68D
Differential SCSI Terminators
Note: A Meritec model 940900-4 or a
DataMate DM5000-5068-11 can
be used to connect a 68 pin
connector to a 50 pin connector.
The drive will now perform 8 bit
transfers.
SCSI Bus Termination Power
Termination power is optionally
provided for systems that desire to use
it. In order to use the termination power,
the user needs to install a jumper
between
pins 1 and 2 of the TermPower
Block. The jumper should only be
installed on one device, which should
be the last device on the SCSI bus. 68
pin models can source up to 2.0 Amps
of current at 5.0 Volts (±5%) for
termination power. 50 pin models can
source up to 1.5 Amps of current at 5.0
Volts (± 5%) for termination power.
SCSI Bus Termination Power Short
Circuit Protection
The ANSI SCSI specification
recommends for devices that optionally
supply TERMPWR, to include current
limited protection for accidental short
circuits. It also recommends that the
maximum
current available for
TERMPWR should not exceed 2 Amps.
UL has a different requirement that they
call the 8 Amp rule. This rule states that
when a power source leaves an
enclosure (like SCSI TERMPWR in the
SCSI cable), it must trip 8 Amps of
current within 1 minute. The drive limits
current to 2.0 Amps through the use of
a resettable fuse mounted on the
electronic card. Systems may also
provide short circuit protection for drive
supplied TERMPWR by limiting the
current of the 5v power it supplies to the
drive.
Operating Environment
The drive operates within its’
performance
limits
when the following
environment is maintained. Product life
calculations are based on the nominal
environment for a typical application.
Humidity
Operating
5% to 90% non-condensing
Storage
5% to 90% non-condensing
Shipping
5% to 95% (applies at the
packaged level)
Wet Bulb Temperature
Operating and
Storage
80 F (26.7
o
C) maximum
Shipping
85 F (29.4
o
C) maximum
Elevation
Operating
-1000 to 10000 feet
(-304 to 3048 meters)
Shipping/Storage
-1000 to 40000 feet
(-304 to 12192 meters)
Temperature
Operating ambient 41 to 122
o
F (5 to 50
o
C)
Operating disk
enclosure 41
to
149
o
F (5 to 65
o
C)
Shipping -40
to
149
o
F (-40 to 65
o
C)
Storage 34
to
149
o
F (1 to 65
o
C)
Temperature Gradient
Operating
36
o
F (20
o
C) per hour
Shipping/Storage
Below condensation
These temperature limits are extremely
important and must not be exceeded at
the worst case drive and system
operating conditions with the drive
randomly seeking, reading and writing.
