PLC programming is now widely used in industry and home automation. In this book, the author describes how the Raspberry Pi 4 can be used as a PLC. Starting with the software installation on the Raspberry Pi and the PLC editor on the PC, the book then moves on to programming after a description of the hardware. It includes interesting examples according to IEC 61131-3 in various programming languages. There is also a detailed explanation of how to use the PLC editor and how to load and execute programs on the Raspberry Pi. The book covers all IEC languages with examples, starting from programming with Ladder Logic (KOP) to Structured Text (ST) and Function Block Diagram (AS). Networking is also addressed, with the Arduino Uno and ESP8266 programmed as ModbusRTU and ModbusTCP modules to access external peripherals. This allows for reading sensors and controlling actuators. I/O circuits that comply with the 24V industrial standard are also of interest. Command overviews for ST and KOP complete the book. After working through the book, the reader will be able to implement their own PLC controls using the Raspberry Pi.