A PLC (programmable logic controller) is a electronic device that is commonly used in the industry. The controller is reading a customised program that has been made by humans several times per second. By electrical wiring the inputs and outputs a process can be controlled. A status can be read, levels can be known or calculations can be made by using digital or analog inputs. These days PLC’s have become a really important component in the industrial automation.
Machines in the industry a frequently using an HMI (Human Machine Interface). The interface between human and machine. This way settings can be changed or machines can be started or stopped. The most important part with processes are to be able to readout important values. This way the process can be monitored and operators can interfere when needed. You are actually looking into the PLC.