Patent ID: 7853787

Claim:
A peripheral device for a programmable logic controller, the peripheral device comprising: an inputting means for inputting peripheral device authentication data being the same as authentication data stored in a storage means of the programmable logic controller; an encryption means for encrypting the peripheral device authentication data used in authentication for authorizing use of the peripheral device itself, encrypting data used in the programmable logic controller, and encrypting authentication data that is established in the programmable logic controller, the authentication data verifies whether or not communication with the programmable logic controller is authorized for the data used in the programmable logic controller; an external storage means for storing at least peripheral device authentication data having been encrypted; an internal storage means for storing at least peripheral device authentication data having been encrypted; a decryption means for decrypting the peripheral device authentication data, the data used in the programmable logic controller, and the authentication data; and a verification means for determining whether or not use of the peripheral device is authorized, by checking peripheral device authentication data read out from the external storage means and decrypted, against peripheral device authentication data read out from the internal storage means and decrypted.