3 MEMORY CONFIGURATION OF THE CPU MODULE
3.1 Memory Configuration
93
3
Program memory/program cache memory
The program memory and program cache memory store necessary programs for the CPU module to perform operations. At
the following timing, data in the program memory is transferred to the program cache memory
*1
and an operation is
performed.
*1 This memory is used for program operations.
• Powered-on
• Reset operation
Application
The program memory and program cache memory store execution programs of program files and FB (function block) files.
Execution programs include instruction codes, statements, and notes.
Data to be allocated
The file header area
*1
and the execution program area (including reserved area for online change) that exist in program files
and FB files are allocated to the program memory.
*1 Depending on the model and firmware version of the CPU module, the file header area is allocated to the data memory. ( Page 94
Destination of the file header area)
Data allocation and procedure of read/write operations
The following figure shows the data allocation of the program memory and program cache memory and the procedure of read/
write operations from/to the programmable controller.
*1 Program restoration information includes the information required to read a program from the programmable controller with the
engineering tool.
*2 Depending on the model and firmware version of the CPU module, the destination of the file header area is the data memory. (
Page 94 Destination of the file header area)
For read/write operations from/to the programmable controller, refer to the following.
GX Works3 Operating Manual
(1) When data is written to the programmable controller, the file header, execution program, and reserved area for online change are written to the program
cache memory, and program restoration information is written to the data memory.
(2) After being written to the program cache memory, the data is automatically transferred to the program memory.
(3) When data is read from the programmable controller, the file header, execution program, and reserved area for online change are read from the program
memory, and the program restoration information is read from the data memory.
(4) After the CPU module is powered off and on or is reset, the data in the program memory is transferred to the program cache memory and operations are
executed.
(1)
(1)
(2)
(3)
(1)
(3)
(3)
(4)
+
Data memory
Program cache
memory
Program memory
When the data is written to the
programmable controller
When the CPU module is powered
off and on or is reset
Engineering tool
When the data is read from the
programmable controller
Inside of the CPU module
File header area
*2
Program restoration
information area
*1
Program file
Execution program area
Reserved area for
online change
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