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

23.4

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.
Memory
CPU buffer memory
Refresh area
Fixed scan
communication area
The Refresh Area in the
Fixed Scan
Communication Area
*1 Data cannot be written to the areas of other CPU modules.
23 MULTIPLE CPU SYSTEM FUNCTION
344
23.4 Data Communication Between CPU Modules
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.
CPU buffer memory
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 Description
method
Communication through This area is used to read/write data from/to the areas of
direct access the host CPU module or other CPU modules.
Page 356 Communication through direct access)
Communication through Data communication is conducted through refresh at
refresh END processing. ( Page 352 Communication
through refresh)
Communication through This area communicates the data to the fixed scan
direct access 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. ( Page 356 Communication
through direct access)
Communication through The refresh operation is conducted at the fixed scan
refresh communication cycle. ( Page 352 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.
*1
(
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
347 Setting fixed scan communication
area)