Chapter 6 Symbol Variables 6.3 Example An example of creating a ladder diagram is shown in chapter 4. In section 5.6.1, the program created in chapter 4 is rewritten by means of reorganizing the structure of the POU and TASK. In the following sections, the device names in the program created in section 5.6.1 will be replaced by symbols. 6.3.1 Planning a Symbol Table The symbols which correspond to the device names in the program created in section 5.6.1 are listed in the following table. Please refer to the descriptions below for more information.
6-43 Original devic e Identifier Address specified Declaration position Function name X0.0 START BT _ X0.0 Global symbol table START button X0.1 STOP BT _ X0.1 Global symbol table STOP button X0.2 InP SNR 1 _ _ X0.2 Global symbol table In position sensor 1 X0.3 InP SNR 2 _ _ X0.3 Global symbol table In position sensor 2 X0.4 CNT SNR _ X0.4 Global symbol table Counting sensor Y0.0 CONVEYER Y0.0 Global symbol table Conveyer Y0.1 TRIG 1 _ Y0.1 Global symbol table Trigger signal for injector 1 Y0.2 TRIG 2 _ Y0.2 Global symbol table Trigger signal for injector 2 M0 RUNNING A device address is assigned automatically.
Global symbol table Operation flag M1 COMPLETE A device address is assigned automatically. Global symbol table Completion flag M2 ERROR A device address is assigned automatically. Global symbol table Error flag