4.A2CCPU
------------------
MELSEC-A
4.1.1 Repeated operation processing
Sequence programs are written by the peripheral device and stored to the
A2C user program area (maximum 8K steps).
The A2C reads
the
required program sequentially from the
user
program
area and performs
the
repeated operation processing in
order
of
step
0 to
the [END)(FEND) instruction.
I
(1) Stored program system
Sequentially reads and operates the program stored in
the
user pro-
gram area.
(2) Scanning
Operates
the
program in
order
of
step
numbers from
step
0 to the
[END)(FEND). •
Flg.4.1
Sequence
Program
Operation
Processing
I
Step number Sequence program
0
LD
XOOO
n
1
OR
YOlO
2
ANI
XOO1
3
OUT
YOlO
,
+
to
,
J
END
4.1.2
Initial processing
Initial processing initiates
the
sequence program operation processing. The
following initial processing is executed when
the
A2C is turned ON or reset
by
the
RUN key switch.
Initial processing time is 2 to 3 seconds
though
it varies with system con-
411
figuration
(1) I/O modules initialization
Resets and initializes
the
I/O modules.
(2) Data memory clear
Clears the
data
memory which is not latched by
the
peripheral.
(3) Link parameter setting
In
the
case of a MELSECNET link station, link parameter data is set to
a data link module before starting data link.
4-4
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