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1.3
INTERFACE CONNECTORS
The interface connectors on the Kennedy Model 331
cartridge transport are designed for twisted pair in-
puts and outputs.
The mating interface connector
consi'3ts of one 44 pin Cinch Jones. Refer to Figure
1-4 for interface assignments.
1.4
INTERFACE SIGNAL CHARACTERISTICS
The tape unit responds to zero-volt true inputs' and
provides zero-volt true outputs.
Logic 1
=
Ov to
+0.4 vdc, while logic 0
=
+2.8 vdc to +5 vdc. Each
signal 'input is terminated in such a manner as to
provide matching for twisted pair cables (see Figure
1-2). Each output line is driven with an open collector
dri ver.
For best results the typical interfacing
circuit configurations shown on Figure 1-2 should be
used. The recommended twisted pair cable will re-
duce the magnitude of intercable crosstalk. Unless
otherwise specified, all wires should be 24 AWG
minimum, with a minimum insulation thickness of
0.01 inch. Each pair should have not less than one
twist per inch, and cable length between transport
and control unit should be no more than 20 feet.
The input receiver circuits, due to zero true current
sinking logic design, will interpret a disconnected
wire or removal of power at the format control unit
as a logic zero or false condition. The logic 1 or
true state requires 25
rnA
current sink with less than
0.4 volt •. The logic 0 or false state will be +3 volts
due to the input matching resistors. Each output line
is driven with an open collector current· sinking logic
driver which is capableof sinking up to 40 milliamp-
eres in the true state. All outputs are disabled' when
the tape unit is not on line and selected.
1.5
TAPE MOTION COMMANDS
The Model 331 responds to four input tape motion
. commands: RUN FORWARD, RUN REVERSE, FAST
FORWARD and FAST REVERSE. The transport in-
cludes a linear ramp generator which drives the cap-
stan servo and provides linear accelerations from
full stop to required speed, and linear deceleration
from run to stop. Start and stop operations occur
within the interrecord gaps. The ramp time is 30
milliseconds for the standard
synch~onous
speed
(25 ips).
Ramp time for 25 ips is adjusted so that
the amount of tape travel during the ramp-up or
ramp-down is always 0.375 inch.
The ramp time and tape travel during the ramp must
be taken into consideration when writing andgapping.
A delay is required before. writing to insure that the
1-2
106-0331-200
tape is up to speed, and to allow read after write. An
additional delay is required before terminating RUN
FORWARD during a write mode to allow for the spac-
ing between the read and write heads. The timing
diagram, Figure 1-3, provides the necessary infor-
mation to produce properly formatted tapes.
1.6
CONTROL SIGNALS
Pin U - RUN FORWARD COMMAND (RF). A level
that when true and the transport is ready causes tape
to move forward at the normal speed. When the level
goes false, tape motion ramps down and ceases.
Pin T - RUN REVERSE
C9MMA~D
(RR).
A level
that when true and the transport is ready causes tape
to move in the reverse direction at the normal speed.
Pin S - FAST REVERSE COMMAND (FR). A level
that when true and the transport is ready causes tape
to move in the reverse direction at the search speed.
When the level goes false, tape motion ceases.
Pin R - FAST FORWARD COMMAND (FF). A level
that when true and the transport is ready causes tape
to move in the forward direction at the search speed.
When the level goes false, tape motion ceases.
Pin
J -
CARTRIDGE RELEASE (CR). Apulse which
will cause the cartridge to be ejected. The cartridge
release solenoid is actuated on command from the
interface, releasing the 3M cartridge whenever CAR-
TRIDGE RELEASE goes true.
To protect the car-
tridge release solenoid, the input command is inter-
nallytimed out
in
the event that CARTRIDGE RELEASE
is not turned off after the cartridge has been ej ected •
Pin N - WRITE ENABLE (WEN). A level that when
true and when a cartridge with the write plug in the
write position has been mounted on the transport
allows writing of data •
1.7 STATUS OUTPUTS
Pin P - READY (RDy). A level that is true when the
tape transport mechanical interlocks are made. When
true, the transport is ready to receive a remote
command.
Pin H -PHOTOCELL B. Output levels which provide
position information for determining load point, EOT,
BOT, end of tape warning, etc.
NOTE:
It
is required that the photocell
outputs be decodecl and stored in order
to accurately deterinine poSition on tape.
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