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7)
Pulse/Continuous Logic
Subsequent
logic
can
be driven
either
by
the input latches or
by
the
User
Control
Interface
inputs.
Switching
between
these
two
sources
is
effected by
tri-state
gates
IC40b, IC41b.
Each
set of four
gates
can be thought
of as a
4PST
switch.
When
the Disable
node
for
a
switch
is
HIGH,
the switch
is
OFF; when
it
is
LOW,
the switch
is
ON.
The
outputs
of the
switches
IC4Qb and IC41b
are
connected
in
parallel,
pairwise,
switching the
AUTO,
BYPASS,
SYNTH
FROM
L,
and
SYNTH
FROM
R
lines
between
the input latches
and
the User.
Control
Interface
inputs.
IC33b
is
a
logical
inverter
which
assures that only
one switch
is
ON
at a
time.
In
Pulse
mode, IC41b
is
always
ON.
In this
mode, IC40a
ordinarily
connects
the
User Control
Interface inputs
to
the input
latches, unless
IC40a
is
turned
OFF
by
a
command
from
the
Automation Lockout
circuit or
by the
User Control
Interface
Status Sensor detecting that
two
or
more
User Control
Interface inputs are active
simultaneously.
In
Continuous
mode, IC4Qa
is
always
OFF,
so that
the
User
Control Interface
inputs
can never
affect the state
of the input latches.
Meanwhile, IC41b
is
ON
until
IC32b
detects
activity
on
a
User
Control
Interface input
line.
A
3
soon
as this
occurs,
IC40b
is
switched
ON
and IC41b
is
switched
OFF,
connecting
the
User
Control
Interface inputs directly
to
subsequent
logic
and
permitting these
inputs to control
machine
status as long as
User Control
Interface input activity
is
detected.
8)
User
Interface Status Sensor
This consists of
IC32 and
associated
circuitry.
When
no
User
Control
Interface
inputs
are
active, pins 3
and
5 of
IC32
are pulled
to
ground by R316.
The
outputs
of
IC32a and IC32b
are
both
HIGH
(towards
+13V).
When
one User Control
Interface input
is
activated, pins
3
and
3
of
IC32
are pulled
to
-2.7V.
Since
pin
6
of
IC32
is
at -1.5V,
while
pin
2
of
IC32
is
at -4.0V,
this
turns
the
output
of
IC32b
LOW
(towards -15V) but
leaves
the
output
of
IC32a
HIGH,
indicating
normal "User
Line Active"
status.
When more
than one
User Control
Interface input
is
activated, pins
3
and
5
of
IC32 go below -4.0V and both
IC32a
and IC32b go
LOW,
indicating a
fault
condition.
When
IC32b goes
LOW,
it
turns
on the
appropriate yellow
STANDBY
lamp
(by
turning
on
Q311
to
supply current
to
the "tree"
which decodes
the lamps),
and
also,
in
Continuous mode,
turns
IC40b
ON
and IC41b
OFF.
When
IC32a
goes
LOW,
it
turns off
IC40a and IC40b and
turns
on IC41b,
disconnecting
the
User Control
Interface inputs
from
all
logic.
When
activated, the
Automation Lockout
circuit
forces pin
1
of
IC35a
to
-15V, thus
forcing pin
2
of
IC32a
to
-15V and
preventing detection
of a fault condition.
(Such
detection
would
otherwise cause
a state
change
to
AUTO,
contrary
to
the intent of
the
Automation Lockout
function.)
6-9
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