To learn about plc working principle we discuss a simple example in which we study its manual process control, then relay control and finally how we can control this process by plc. First of all, we discuss manual control or process. In given diagram, we take an example of a motor control mixer. In this process we are using two sensors, the In a TV's cathode ray tube, the stream of electrons is focused by a focusing anode into a tight beam and then accelerated by an accelerating anode. This tight, high-speed beam of electrons flies through the vacuum in the tube and hits the flat screen at the other end of the tube. In a 20x4 LCD module, there are four rows in display and in one row twenty character can be displayed and in one display eighty characters can be shown. This liquid crystal module uses HDD44780 (It is a controller used to display monochrome text displays) parallel interfacing. The liquid crystal display interfacing code is easily accessible. Understanding the basic working principle of the digital display technologies will help understand the following sections more easily. A digital image is produced by a rectangular array of picture elements (pels or pixels). Each pixel in the display panel is made of three sub-pixels for the three additive primary colours: red, green and blue. Plug in the USB connector of the Arduino to power the LCD. You should see the backlight light up. Now rotate the potentiometer until one (16×2 LCD) or 2 rows (20×4 LCD) of rectangles appear. Rotate the potentiometer until you see a row of rectangles appear. You can tweak the contrast later if needed. BQWw.

lcd panel working principle