HMI Web Control with the ESP8266 I/O Board and Raspberry PI

Here is an application for the ESP8266 I/O Board to control and monitor electrical loads at home or in a plant via the Internet using a PC, cell phone or tablet. With the ESP8266 I/O module and appropriate software this is no problem anymore.

To build such an application, you need an ESP8266 in the home WLAN with the appropriate Arduino software which communicates with a remote server at a web hoster. In the meantime, there are providers who offer space for your own website for little money.

The application works as follows:

The ESP8266 sends its data via HTTP POST to a PHP program on the server. The PHP program on the server stores this data for an HTML application, which fetches the data via AJAX (JavaScript) into the web page. So it is already possible to read in and display measured values and switches.

With the buttons on the web page data are stored by AJAX over the PHP program on the web server. This data is retrieved by the ESP8266 on the I/O board and switches the consumers or outputs a voltage from 0 to 10 volts.

The PHP program offers much more possibilities than just handling the data traffic. So it is also possible to send e-mails in case of an alarm in the system or to store the data in a mysql database and display it on the web page.

Here is an example web page showing the status of four inputs. With the buttons Relay ON and Relay OFF four electrical consumers can be switched. Furthermore it is possible to display a voltage or temperature, humidity etc. and vice versa to send a voltage value (setpoint) to the ESP8266.

Basically this also works with the Raspberry PI or other computers connected to the network. Besides, the ESP8266 can take over the function of a controller.

Questions and suggestions to this article are welcome.