LADDER PROGRAM UNAUTHORIZED-USE PREVENTION SYSTEM LADDER PROGRAM UNAUTHORIZED-USE PREVENTION METHOD AND ENGINEERING TOOL

摘要

In the ladder program misuse prevention system, a program is executed for a ladder program encrypted using a vendor secret key, using a vendor public key paired with a vendor secret key, and then decoded to a ladder program that has been decrypted. Controller secrets paired with the controller public key in engineering tools that perform encryption using the controller public key and in ladder programs encrypted using the controller public key so that they operate on the controller and not on other programmable controllers. A programmable controller is used for decoding using a key and executing a ladder program decoded using a controller secret key.