Mitsubishi Electric MELSEC iQ-R Series - Communication through Direct Access

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23 MULTIPLE CPU SYSTEM FUNCTION
23.4 Data Communication Between CPU Modules
Communication through direct access
This method uses programs to communicate with other CPU modules. The following table lists the communications using the
direct access method.
Specification method thorough CPU buffer memory access device
Specify the CPU buffer memory as "U3En\Gn" or the fixed scan communication area as "U3En\HGn" when accessing the
memory or area. ( Page 475 CPU Buffer Memory Access Device)
■Obtaining information stored on the CPU buffer memory
Access the CPU buffer memory.
■Obtaining information stored on the fixed scan communication area for other CPUs
Access the fixed scan communication area on the host CPU module. Obtain data sent to the fixed scan communication area
on the host CPU module at the fixed scan communication cycle.
Communication method Description Instruction to be used
Communication using CPU buffer
memory
Data between CPU modules are transferred using any
area on the CPU buffer memory.
• FROM/TO instruction
• DFROM/DTO instruction
• Instruction using the CPU buffer memory access
device (U3En\G)
Communication using the fixed scan
communication area
Data between CPU modules are transferred using the
fixed scan communication area.
Instruction using the CPU buffer memory access device
(U3En\HG)
Communication by a dedicated
instruction
Data between CPU modules in the multiple CPU system
are transferred and/or control commands are sent to
other CPU modules by using a dedicated instruction.
DDWR/DDRD instruction and others
CPU No.1 CPU No.2
CPU No.3
Host CPU module
U3E0\G0
U3E0\G8000
(U3E1\)*1 G0
U3E0\HG0
U3E0\HG1024
(U3E1\)*1 HG0
U3E2\HG0
U3E2\HG1024
CPU
buffer memory
Send area
of CPU No.1
Receive area
of CPU No.2
Receive area
of CPU No.3
Send area
of CPU No.2
Receive area
of CPU No.1
Receive area
of CPU No.3
Receive area
of CPU No.1
Receive area
of CPU No.2
Send area
of CPU No.3
Fixed scan communication area
Fixed scan communication area
Fixed scan communication area
Acquire information
on other CPU
modules.
CPU
buffer memory
CPU
buffer memory
U3E2\G0
U3E2\G8000