CitectSCADA uses a hardware key to help prevent license infringement. The hardware key is a physical key that plugs into either the parallel port or USB port of your computer. The hardware key contains details of your user license, such as type and I/O point limitAn individual digital (or analog) variable read from an I/O device. only counts physical points (and counts them only once, no matter how many times they are used). The point limit is the maximum number of I/O device addresses that can be read and is specified by your license. When you run the point count of your project is checked against the point limit specified by your Hardware Key..