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3. LINKING TO THE A2CCPU
MELSEC-A
(1)
Communications processing of control I/O signals is described below.
(a) During sequence program execution, communication
of I/O signals
between the A2CCPU and the A64RDC is executed by suspending
the sequence program execution
every 10 msec. During com-
munications, input signal data is stored in the input (X) received-data
area, and data stored in the output send data area is output to the
A64RDC.
(b) After the END instruction of the sequence program is executed, data
in the output (Y) operation area where the operation result is stored
is refreshed to the output (Y) send data area. Then, data stored in
the input (X) received-data area is refreshed to the input (X) opera-
tion area.
I
Scan
time
I
1-
Sequence
program
operation
-1
I O
msec
'
L
I
I
L
J-
L
10 msec
10 msec
END
END
Communications with an A64RDC
(2) Writing data to the A64RDC buffer
(c) The TO instruction information is written to the request-to-communi-
cate registration area
by the execution of the TO instruction, and
registration of the TO instruction information is completed by execu-
tion of the PRC instruction.
(d) The PC CPU starts processing instructions of the next and following
steps when the TO instruction information has been registered.
(The instruction processing will
not wait for
a
transmission-com-
pleted response.)
The TO instruction information stored in the request-to-communicate
registration area is transmitted in several steps to the A64RDC. This
is done via the word data send area to the A64RDC after execution
of the END instruction.
(e) The communications-completed flag
( M l ) designated by the PRC
instruction is turned
ON for
one scan from step
0
of the scan
immediately after the response of send-completed transmitted from
the A64RDC is received by the A2CCPU. Upon completion of the
send, the TO instruction information stored
in the request-to-com-
municate registration area is cleared.
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