A programmable controller to control a control machine includes an arithmetic processor, a storage, and a selector. The storage stores a plurality of definition files and a control program. The definition files each define a corresponding relationship between specification information and a plurality of control elements of the control machine. The specification information specifies an input-output end from and to which the programmable controller receives and outputs at least one of a command and information. The control program is executable by the arithmetic processor to input and output at least one of the command and the information from and to the control elements based on at least one of the definition files. The selector is configured to select the at least one definition file to use as a basis on which the arithmetic processor executes the control program.