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Operation
4.10
Selecting
switching
parameters
The
Model 707
A
has
three
switching parameters
that
are
user-modified: the
programmed
settling
time,
make-before-
break rows,
and
break-before-make rows.
These
values
of
these
parameters
are
in
effect for
all
relay
switching
until
they
are
changed. Figure 4-14
shows
the front
panel
keys of
the
switching group.
Figure
4
14
Switching keys
4.10.1
Programmed
settling
time
The
programmed
settling
time
is
a variable switching delay
that
can be used
to
lengthen
the fixed
delay of
the relay
(hardware)
settling
time.
You
can
select, in
1msec
incre-
ments,
up
to
65 seconds of
an
additional
switching
delay.
If
an
additional trigger
is
received
during
this
time,
it
is
pro-
cessed and
the
message
NOT
SETTLED
is
displayed.
At
the
end
of
the
programmed
settling
time, the
Model
707
A
sets
the
MATRIX
READY
output
true.
To
view
or
change
the
programed
settling
time, press the
SETl'LING
TIME
key
in
the
SWITCHING
key
group.
The
value of
the
programmed
settling
time value
is
displayed
as:
SETL
00000
mS
To
exit the
display
without
changing
the value, just press
CANCEL.
To change
the value, enter
between
0-65(XX) with
the data entry
keys
and
press
ENTER.
This
action also
returns
the
display
to
the
RELAY
STEP
and
MEMORY
STEP.
The programmed
settling
time
is
in
effect for
all
crosspoint
relay open/close operations
until
it
is
reprogrammed.
Its
effect
on
trigger
response times
is
described
in
paragraph
4.11.
4.1
0.2
Make/break and break/make rows
Make-
before-break switching of
relays
is
defined as con-
necting
a
new
circuit
before disconnecting the present
cir-
cuit.
It
is
used
to
eliminate
transients
caused by switching
between
current
sources.
Break-before-make switching
means
to
disconnect
the
present
circuit
before
connecting
a
new
circuit.
It is
used
to
avoid
momentary
shorting
of
two
voltage sources.
Both
of
these
switching operators
are
sup-
ported
by
the
Model
707A.
Rows
of
crosspoint
relays are user-selectable for
make/break
(make-before-break),
break/make
(break-before-make), or
"don't
care"
operation.
The
selections
will
be
in
effect for
all
switching
until
new
choices
are
made.
When
make/break
or
break/make
operation
is
chosen,
the
Model
707A
automati-
cally
switches
the crosspoint relays
through intermediate
set-
ups
to
perform
the
following
steps;
1.
Crosspoints
in
break/make rows
are
opened.
2.
Crosspoints
in
make/break rows
are closed.
3.
Crosspoints
in
make/break rows
are
opened.
4.
Crosspoints
in
break/make rows
are closed; crosspoints
in
"don't care"
rows
are
opened
or closed accordingly.
These
steps are transparent
to
the user
except
for the
in-
creased
settling
time.
If
either
make/break
or
break/make
rows
are
not
selected, the
appropriate
steps in the
previous
list
are deleted
and
the
total
settling
time
decreases.
As
make/
break
and
break/make
operations
affect settling
times
and
trigger
response, these operations
are further
discussed
in
paragraph
4.11.
The
front
panel
MAKE/BREAK
and
BREAK/MAKE
keys
are
used
in
conjunction with
the data entry
keys
to select
rows
for operation as
make/break
or
break/make.
When
a
row
designation
(A-H)
is
selected
and
displayed
by
itself,
the
MAKE/BREAK
and
BREAK/MAKE
keys toggle
the
state
of
the
MAKE/BREAK
or
BREAK/MAKE LED
for that
row
and immediately reprograms
the
Model
707
A
for the
new
operation.
The
INVALID INPUT
message
is
displayed
briefly
if
you
press the
MAKE/BREAK
or
BREAK/MAKE
key without
first
selecting a
row
or
if
a
row/column
address
is
displayed
instead
of
just
a row.
Note
that
selecting a
row
for
make/break
de-selects
it
for
break/make and
vice
versa.
The
various front
panel opera-
tions are
listed in
Table
4-7.
4-19
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