They are separated “optically” or, in other words, the signal is transmitted through light. Optical isolation means that there is no electrical connection between the external world and the CPU unit. This is usually done through optical isolation, and this function can be seen in the following image. The input adjustment module changes the actual logic level to a level that suits the CPU unit (for example, the input of a sensor that operates with 24 VDC must be converted to a 5 VDC signal so that the CPU can process it).
inductive sensors can register metal objects). They can feel the presence of some parts, measure temperature, pressure, or some other physical dimension, etc. You can get sensors for different purposes. The sensors are generally used as inputs for PLCs. One of the most frequent analog signals is a current signal of 4 to 20 mA and a millivolt voltage signal generated by several sensors. Therefore, the input signals can be logical (on / off) or analog. To detect a work piece, see a mechanism in motion, check the pressure or the level of liquid, you need specific automatic devices such as proximity sensors, marginal switches, photoelectric sensors, level sensors, etc.