Open Source Compact Controller RevPi Compact based on the Raspberry Pi. The RevPi Compact is a space-saving, compact open-source controller built on the Raspberry Pi 3+ Compute Module. For connecting to sensors and actuators, the device features eight digital and analog inputs as well as eight digital and two analog outputs. Numerous interfaces are already included as standard: two Ethernet interfaces, each with its own MAC address, allowing the compact controller to be integrated into two separate networks simultaneously, four USB A ports, one HDMI port, and a 4-pin RS485 interface. Modbus TCP/RTU devices can be connected directly. The quad-core processor with 1 GB RAM of the Raspberry Pi Compute Module 3+ offers high performance and efficiency. The operating system is a customized version of Raspbian, which includes a real-time patch and a process image. Applications can be developed directly in Python, C, or Node-RED, among others. Optionally, professional control software such as Codesys or logi.CAD can be used for an additional fee. Due to its small size, the device is also ideally suited for DIN rail mounting in distribution cabinets, as used in building automation.