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23 MULTIPLE CPU SYSTEM FUNCTION
23.4 Data Communication Between CPU Modules
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.
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.
*1 Data cannot be written to the areas of other CPU modules.
Communication
method
Application Description
Data communication with
CPU buffer memory
This method is used when data is sent or
received at the timing of each CPU
module.
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).
Data communication with
fixed scan communication
area
This method is used when data is sent or
received through adjusting the timing
between 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.
Memory Communication
method
Description Area size
CPU buffer memory Communication through
direct access
This area is used to read/write data from/to the areas of
the host CPU module or other CPU modules.
*1
(
Page 356 Communication through direct access)
512K words fixed
Refresh area Communication through
refresh
Data communication is conducted through refresh at
END processing. ( Page 352 Communication
through refresh)
Fixed scan
communication area
Communication through
direct access
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. ( Page 356 Communication
through direct access)
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)
The Refresh Area in the
Fixed Scan
Communication Area
Communication through
refresh
The refresh operation is conducted at the fixed scan
communication cycle. ( Page 352 Communication
through refresh)
CPU buffer memory
Refresh area
Refresh area
Fixed scan communication area
Send area of CPU No.4
Refresh area
Send area of CPU No.3
Refresh area
Send area of CPU No.2
Refresh area
Send area of CPU No.1
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