I
4. A2CCPU
--------------------
MELSEC-A
IREMARKSI
(1)
":
An
infinite
loop
may
be
caused
if a
program
execution
sequence
is
jumped
to
a
smaller
step number because of a CJ instruction.
Example:
xo
xo
OJ
An
infinite
loop
is caused if
there
is no
jump
in-
struction
calling
for
a
jump
to a
step
beyond
step
CJ PO to
between
point
PO
and
step
CJ
PO,
thereby
precluding
the
execution
of
the
END instruction.
•
(1) Data
stored
in
special
registers
09017
to
9019
a)
09017:
Smallest
value
of
scan
time
b)
09018:
Present
value
of
scan
time
c)
09019:
Largest
value
of
scan
time
4.1.9
RUN, STOP, PAUSE operation processing
The A2CCPU operates in one of the following
three
states:
(a) RUN state
The PC CPU operates
the
sequence program repeatedly from step
to
the
END (FEND) instruction.
(b) STOP state
All
outputs
(Y) are
turned
off and sequence program operation is
not executed.
(c) PAUSE state
Execution of a sequence program is suspended. The status of all
outputs
(Y) before entering
the
PAUSE state are saved.
The
PC
CPU's
operation
processing
in
each
operation
state
is
described
below.
4-13
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