Abstract: To decode a file name set to a PLC to the same name even if a plurality of external devices using different character-code sets are connected to the PLC, the PLC includes a system unit that actuates the control file using a multilingual character-code set A, a character-code conversion table that associates character codes relating to a plurality of character-code sets with one another for every character, and a character-code management unit that converts description of the name of the control file between the description relating to the multilingual character-code set A and that relating to the local character-code set A using the character-code conversion table when the name of the access-target control file is transferred between the external device using the local character-code set A and the system unit.

Abstract: To decode a file name set to a PLC to the same name even if a plurality of external devices using different character-code sets are connected to the PLC, the PLC includes a system unit that actuates the control file using a multilingual character-code set A, a character-code conversion table that associates character codes relating to a plurality of character-code sets with one another for every character, and a character-code management unit that converts description of the name of the control file between the description relating to the multilingual character-code set A and that relating to the local character-code set A using the character-code conversion table when the name of the access-target control file is transferred between the external device using the local character-code set A and the system unit.

Abstract: A PLC includes a detachable first storing unit configured to store first key data and protected from access, a second storing unit configured to store a user program in association with second key data, and a startup processing unit configured to execute startup processing for the PLC itself when a power supply is turned on. The startup processing unit includes a startup-processing-stop determining unit configured to read out the first key data stored by the first storing unit inserted in the PLC itself and the second key data stored in the second storing unit and associated with the user program and determine, based on collation of the read-out two key data, whether the startup processing is continued or the startup processing is stopped and abnormal processing is executed.