Data Communication Between Cpu Modules; Memory To Be Used - Mitsubishi Electric MELSEC iQ-R-R00CPU User Manual

16.4

Data Communication Between CPU Modules

CPU modules within a multiple CPU system can send and transfer data to each other. The refresh communication and direct
access communication enable data writing or reading between CPU modules. The following table lists the data
communication method.
Communication method
Data communication with CPU buffer
memory
Data communication with fixed scan
communication area

Memory to be used

CPU buffer memory is utilized for data communication between the CPU modules.
Memory configuration of CPU buffer memory
This section describes the memory configuration of CPU buffer memory.
CPU buffer memory
Memory
CPU buffer memory
Refresh area
Fixed scan communication area
The Refresh Area in the Fixed Scan
Communication Area
Application
This method is used when data is sent
or received at the timing of each CPU
module.
This method is used when data is sent
or received through adjusting the
timing between CPU modules.
Refresh area
Send area of CPU No.1
Refresh area
Send area of CPU No.2
Refresh area
Send area of CPU No.3
Refresh area
Send area of CPU No.4
Refresh area
Communication method
Communication through direct
access
Communication through refresh
Communication through direct
access
Communication through refresh
Description
The CPU module for sending the data writes data into the CPU Buffer
memory of the host CPU module. The CPU module for receiving data reads
data from the CPU Buffer memory of the sender CPU module (other CPU
modules).
The CPU module for sending the data writes data into the fixed scan
communication area (send area) of the host CPU module. The CPU module
for receiving data reads data from the fixed scan communication area
(receive area) of the host CPU module of the send source CPU module.
Description
This area is used to read/write data to
the areas of the host CPU module or
other CPU modules.
Data communication is conducted
through refresh at END processing.
This area communicates the data to
the fixed scan communication area of
the host CPU module, and is used
when the host CPU module area and
another CPU module area transfer
the data at the fixed scan
communication cycles.
The refresh operation is conducted at
the fixed scan communication cycle.
16 MULTIPLE CPU SYSTEM FUNCTION
16.4 Data Communication Between CPU Modules
Area size
512K words fixed
It is possible to change within the
range of 0 to 24K words in total. The
send area as per unit can be set
within the range of 0 to 12K words.
( Page 300 Setting fixed scan
communication area)
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