HomeMaster MiniPLC is an ESP32-based DIN-rail programmable logic controller with ESPHome support, multiple industrial I/O options and local Home Assistant integration.
HomeMaster MiniPLC is a compact DIN-rail PLC controller built around an ESP32-WROOM-32D-N16 module and designed for residential and light industrial automation. ESPHome comes pre-installed, allowing the controller to connect directly to Home Assistant over a local network without relying on cloud services. The hardware is open source under the CERN-OHL-W v2 licence, while its firmware and configurations are available under the MIT licence.
The controller provides six SPDT relay outputs rated for up to 3 A at 250 V AC, along with four isolated 24 V digital inputs. For analogue applications, it includes four 0–10 V inputs with 16-bit resolution and one 0–10 V output with 12-bit resolution. There are also two PT100/PT1000 RTD channels, two 1-Wire buses for DS18B20 sensors and an RS-485 Modbus RTU master interface.
Built around a dual-core 32-bit Xtensa ESP32 processor running at up to 240 MHz, the MiniPLC provides 520 KB of internal SRAM and 16 MB of flash storage. Wireless connectivity includes 2.4 GHz Wi-Fi and Bluetooth 4.2/BLE, with an external SMA Wi-Fi antenna. An optional LAN8720-based 10/100 Mbps Ethernet interface is also available, although ESPHome cannot operate Wi-Fi and Ethernet simultaneously. A microSD card slot, 128 × 64 OLED display, four buttons, 12 status LEDs, buzzer and PCF8563 real-time clock add further control and monitoring functions.
For installation, the controller supports either 24 V DC or 85–265 V AC input, with only one power input used at a time. It measures 157.4 × 91 × 58.4 mm, occupies nine DIN modules and weighs 300 grams. The enclosure is rated IP20 and is intended for indoor operation between 0°C and 40°C. The device is CE marked, with EMC testing reported against EN 55032 Class B emissions and EN 55035 immunity requirements.
The open-source design is accompanied by schematics, documentation and the EU Declaration of Conformity, which are available through GitHub. Security features include an encrypted native API, with each device generating its own encryption key during setup and an initial configuration window limited to 15 minutes after power-on. The controller is also officially recognised as “Made for ESPHome.” HomeMaster lists limitations including the 3 A relay rating for heavier or inductive loads and shared GPIOs between the RTD inputs and USB serial interface.
