CJ2 CPU Unit Software User's Manual - CIP ETI

5 Understanding Programming5-5-2 Types of SymbolsThe following types of symbols can be used.Program Symbols Types of Symbols• Global SymbolsGlobal symbols can be accessed from any task in the CPU Unit.• Local SymbolsLocal symbols can be accessed from only one task.• Network Symbols (CJ2H-CPU6@-EIP or CJ2M-CPU3@ only)Tags can be used from exterior devices to access the I/O memory of the local CPU Unit throughthe network symbols defined in the CPU Unit. Network symbols can also be used in the local CPUUnit. Address AllocationType ofsymbolProgramsymbolsAddresses are allocated to symbols used in programming based on the following factors.• User Specifications• Automatic Allocation using the CX-ProgrammerThe area of memory used for automatic allocations is set by selecting Memory Allocation −Automatic Address Allocation from the PLC Menu in the CX-Programmer.NameGlobal symbolsCX-Programmer project treePLC treeAccessusing networksymbolsNot supportedScopeAccessfrom othertasksAccessfrom thelocal taskAddressand I/Ocomment(without asymbolname)Supported Supported SupportedLocal symbolsProgram treeNot supportedSupportedNot supportedNetworksymbolsGlobal variable table in PLCtreeSupported Supported Supported Not supportedNote “Global” and “local” indicate only the scope of application of the symbol. It has nothing to do with the scope of applicationfor the memory address. Therefore, a warning but not an error will occur in the following cases, and it will be possible totransfer the user program.• The same addresses is used for two different local symbols• The same addresses is used for a global symbol and a local symbol5-46 CJ2 CPU Unit Software User’s Manual