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MELSEC-Q
16 COMMUNICATION BETWEEN CPU MODULES IN MULTIPLE PLC
SYSTEM
(c) There are cases where old data and new data will become mixed up for
each PLC depending on the timing of refreshing the host PLC and reading
data from other PLCs.
When performing the automatic refresh function, create an interlock
program similar to the one shown below that uses the first device to be
refreshed for each PLC, and do not use the data from other PLCs when old
data does get mixed up with new data.
An example of a program set up with the following multiple PLC setting
refresh settings is shown below.
• CPU device: D0
• PLC No.1 transmission points: 1024 points (D0 to D1023)
• PLC No.2 transmission points: 1024 points (D1024 to D2047)
Used for the PLC No.1 interlock
D0
D1023
to
D1024
D2047
to
PLC No.1 transmission device
PLC No.2 transmission device
Transmission data
set in D0 to D1023
Writing
command
D1024.0
D0.0
Interlock with b0 of the PLC No.2
first device (D1024)
b0 of the PLC No.1 first device (D0)
for the use of the interlock is set at
ON when transmission data setting has
been completed.
Example of a program on the transmission side
Operation using the
transmission data
(D0 to D1023)
D0.0
D1024.0
Interlock with b0 of the PLC No.1
first device (D0)
b0 of the PLC No.2 first device
(D1024) for the use of the interlock
is set at ON when operations using
the received data have been completed.
Example of a program on the reception side
Used for the PLC No.2 interlock
Содержание QCPU (Q Mode)
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