The goal of the thesis is to design and build a low-cost PLC (Programmable Logic Controller) controller that is easy to work with and easy to program for users who do not have much experience in this field. It is designed on the ESP32 platform and is general enough to be used for many different purposes. Individual components and devices can be connected to one of the 16 relay outputs for control and sensors to one of the 8 inputs. In the event of a power loss, the data is retained in flash memory in the ESP32 microcontroller. The controller can be programmed in a user-friendly way by setting the states, the conditions for transitions between them, and the corresponding functions of the programmable buttons located on the housing. The controller also supports several modes of operation or control algorithms, from which only one can be selected and active. In this way, the PLC can be pre-programmed for different situations. All controller settings can be changed via the on-screen user interface or via a local web page hosted on the controller. We first tested the controller’s performance in terms of user experience and then in the situation of controlling a pond treatment plant. From both tests, we found that the controller works according to the requirements and objectives and can equivalently replace the existing system.
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