The Modbus protocol is widely used in the industrial sector for communication between systems and controllers. This is usually done with the tried-and-true RS485 interface and conventional copper wire. Here we present a module that allows you to use the Modbus protocol over a wireless local area network (WLAN). The module is built around an Espressif NodeMCU board fitted with an ESP8266 microcontroller. A supplementary Modbus baseboard allows you to work with 24 V signals, which is a common voltage level in the industrial environment. To demonstrate how it all works, the authors built a simple lift door controller.