ESP32LR42 WiFi Relay Module ESP32 4x16A 12V with 2 Digital Inputs MQTT Web HTML

The ESP32LR42 is an ESP32- based WiFi relay module, ideal for home automation, automation, and remote control of electrical loads. It offers 4 relays capable of switching up to 16A each and 2 digital inputs with pull-up, designed for direct connection to volt-free contacts such as alarm contacts, thermostats, limit switches, and sensors.

The normally open (NO) contacts of the relays integrate protective snubbers , making the module also suitable for managing inductive loads such as contactors, solenoid valves, external relays and solenoids, reducing disturbances and electrical arcs during switching.

Power is 12V DC , which can be obtained via a common wall power supply. For stable operation, a 1A or higher power supply is recommended.

Supported control methods

The module can be controlled in several ways, depending on the desired integration:

• Text commands (ASCII) over the network

• HTML commands (calls from browsers or systems that do HTTP GET)

• MQTT for integration with Home Assistant, Node-RED, and IoT platforms

• Integrated web page for browser-based control and monitoring

WiFi connection and installation

The connection is made over a 2.4 GHz WiFi network. To ensure a stable signal, the device must be installed in a location with good WiFi coverage and it is preferable to avoid metal containers that shield the signal.

Configuration

Initial configuration is done via a USB connection to a PC and a serial terminal (e.g., typical settings: 115200 baud, 8N1). After configuration, the module can be controlled via the network using the protocols listed above.

Main features

• ESP32 -based WiFi module

• 4 relays up to 16A

• 2 digital inputs with pull-up for dry contacts

• Snubber on NO contacts for better management of inductive loads

• Power supply 12V DC (recommended ≥ 1A )

• Control via text commands, HTML, MQTT and integrated web page

• Suitable for automation, home automation and remote control of systems

Typical applications

• Home automation (lights, sockets, scenarios, loads)

• Check contactors, solenoid valves, solenoids

• Gate/lock automation (via suitable contactors or relays)

• Management of technical systems, ventilation, pumps (via contactors)

• Integration with Home Assistant / Node-RED via MQTT

• Acquisition of states from clean contacts (alarms, thermostats, limit switches)