Mitsubishi Electric MELSEC Q Series User Manual page 184

(b) Outline of the communication by the program
1) Using user setting area
The data written to the CPU shared memory of the host CPU with a write instruction can be read by another
CPU using a read instruction.
Unlike the auto refresh of the CPU shared memory, it is possible to read up-to-date data directly when this
instruction is executed.
An outline of a process where data written in the CPU shared memory of CPU No.1 with an write instruction
is read by CPU No.2 using an read instruction is shown in Figure 4.40.
CPU No. 1
CPU shared memory
Host CPU operation
information area
System area
Auto refresh area
User free area
Data written with write
instruction
1)
Write with write instruction
sequence program
Execution of
write instruction
CPU No.1 processing
1) Data are written into the user setting area of CPU No.1 with a write instruction.
CPU No.2 processing
2) A read instruction is used to read data from the user setting area of CPU No.1 to the specified device.
For the write/read instruction, refer to Section 4.1.4(1).
For the Motion CPU, the write/read instructions are not usable.
For the accessing method from the Motion CPU and PC CPU module to the CPU shared memory, refer to each CPU module
manual.
2) Read with read instruction
Figure 4.40 Outline of communication by program
CHAPTER4 COMMUNICATIONS BETWEEN CPU MODULES
CPU No. 2
CPU shared memory
Host CPU operation
information area
System area
Auto refresh area
User free area
sequence program
Execution of read instruction
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