Appendices
A-102
NJ-series CPU Unit Hardware User’s Manual (W500)
A-6 System-defined Variables Related to
Hardware
System-defined variables are assigned specific functions by the system. They are registered in the
global variable table, or the local variable table for each POU, in advance.
The variable names cannot be changed. Some of the variables start with an underbar and some start
with ”P_”.
Some of the system-defined variables are read-only and some are read/write.
You read and write the variables with the user program, with communications from external devices,
with the Sysmac Studio, or with an NS/NA-series PT.
The system-defined variables that are related to hardware are classified by functions as follows.
• System-defined Variables for the Overall NJ-series Controller (No Category)
• Clock
•Errors
• SD Memory Card
• Backup
• Power supply
• Version
• PLC Function Module, Category Name: _PLC
•Errors
• PLC Function Module, Category Name: _CJB
• I/O bus status
• I/O bus errors
• Auxiliary area bits for CJ-series Units
Refer to the NJ/NX-series CPU Unit Software User’s Manual (Cat. No. W501) for details.
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