Hardwired logic is fixed and can only be changed by physically altering how devices are connected. On the other hand, programmable control relies on basic logic functions like AND, OR, and NOT, which can be easily changed through programming. These functions are used to create instructions that determine whether a device should be turned on or off. The language used to convey these instructions to the Programmable Logic Controller (PLC) is typically ladder logic. This language represents control

PLC Hardware Explained

7.7 Programmable Logic Devices