Memory Areas And Stored Data; Backup; Index - Omron CP1E CPU UNIT SOFTWARE User Manual

With an E-type CPU Unit or with an N/NA-type CPU Unit without a Battery, the con-
tents of the DM Area (D) *, Holding Area (H), the Counter Present Values (C), the sta-
tus of Counter Completion Flags (C), and the status of bits in the Auxiliary Area (A)
related to clock functions may be unstable when the power supply is turned ON.
*This does not apply to areas backed up to EEPROM using the DM backup function.
If the DM backup function is being used, be sure to use one of the following methods
for initialization.
1. Clearing All Areas to All Zeros
Select the Clear retained memory area (HR/DM/CNT) to Zero Check Box in
the Startup Data Read Area in the PLC Setup.
2. Clearing Specific Areas to All Zeros or Initializing to Specific Values
Make the settings from a ladder program.
If the data is not initialized, the unit or device may operate unexpectedly because of
unstable data.
2-1-2

Memory Areas and Stored Data

The following table lists the CPU Unit memory areas and the data stored in each area.
Memory area and stored data
User Program Area
User Program
Symbol Table
Comments
Program Index
Parameter Area
Setting PLC Setup
I/O Memory Areas
CP1E CPU Unit Software User's Manual(W480)
Caution Caution
Details
The User Program Area stores the object code for executing
the user program that was created using the CX-Programmer.
The symbol table contains symbols created using the CX-Pro-
grammer (symbol names, addresses, and I/O comments).
Comments are created using the CX-Programmer and include
annotations and row comments.
The program index provides information on program sections
created using the CX-Programmer, as well as program com-
ments.
Various initial settings are made in the PLC Setup using soft-
ware switches.
Refer to Section 7 PLC Setup.
The I/O Memory Areas are used for reading and writing from
the user programs.It is partitioned into the following regions
according to purpose.
• Regions where data is cleared when power to the CPU Unit
is reset, and regions where data is retained.
• Regions where data are exchanged with other Units, and
regions that are used internally.
DM Area words backed up to backup memory (built-in
EEPROM) using control bits in the Auxiliary Area.
2 Internal Memory in the CPU Unit
Built-in
RAM
Stored
Stored
Stored
Stored
2
Built-in
EEPROM
Stored
Stored
Not stored
Stored
2-3