Method of optimally compiling PLC command

A method of compiling a PLC (Programmable Logic Controller) command, the method comprising:

• determining a chosen compiler processing scheme chosen from a plurality of compiler processing schemes for a command included in a program to be executed in a PLC;
• executing a command compiler optimized for a rate or a size based on the chosen compiler processing scheme;
• wherein determining a chosen compiler processing scheme includes providing a first setting to automatically choose one compiler processing scheme of the plurality of compiler processing schemes for the command as the chosen compiler processing scheme based on a program size or a remaining data storage capacity in the PLC;
• and
• wherein providing the first setting to automatically choose one compiler processing scheme includes:
• providing a second setting to choose a compiler processing scheme for the rate under a normal condition or to choose a compiler processing scheme for the size when the program size is over a reference size, and
• providing a third setting to choose the compiler processing scheme for the rate under a normal condition or to choose the compiler processing scheme for the size when the remaining data storage capacity in the PLC is below a reference capacity, and wherein executing the command compiler includes:
• determining whether the chosen compiler processing scheme is a simple command processing scheme based on the command when the chosen compiler processing scheme is determined to be the compiler processing scheme for the size;
• responsive to determining that the chosen compiler processing is a simple command processing scheme, executing the command compiler in an assembly language by a direct compiler processing scheme;
• and
• responsive to determining that the chosen compiler processing scheme is not a simple command processing scheme, executing the command compiler in an indirect compiler processing scheme.