The RevPi Connect 4 (4 GB / 32 GB) is based on the Raspberry Pi Compute Module 4 (CM4) and offers a modular design, industrial suitability, and open-source support. It is powered by a Broadcom BCM2711 processor (64-bit Quad-Core Arm Cortex-A72). This version of the RevPi Connect 4 features 8 GB of RAM, 32 GB of eMMC storage, and supports up to ten I/O modules. The interfaces include two Gigabit Ethernet ports, two USB 3.2 Gen1 ports, RS485, a Micro-HDMI port, and a Micro-USB port. The device includes an integrated real-time clock (RTC) and a hardware watchdog. A HAT EEPROM stores device information. The front panel has six RGB LEDs, five of which are individually programmable. It comes with a pre-installed, customised 64-bit Raspberry Pi OS (including a real-time patch and process image). Modbus RTU and Modbus TCP are supported by default. Additionally, control and HMI software can be installed. The RevPi Connect 4 supports protocols such as MQTT and OPC UA and enables the development of custom applications using Node-RED, Python, and C.