There are no physical switch contacts or relay coils operating inside the PLC to produce the logical linkages between input and output, despite the fact that the programme seems to be a ladder logic diagram with switch and relay symbols.
A PROGRAMMABLE LOGIC CONTROLLER (PLC) is an industrial computer control system that continually monitors the status of input devices and controls the state of output devices using a bespoke programme. That is, you can mix and match the different types of Input and Output devices to meet your needs.
To begin, ensure that the PLC is receiving sufficient power from the transformer to power all of the loads. If the PLC is still not operating, look for blown fuses or a power supply drop in the control circuit. If the PLC does not turn on despite adequate power, the fault is most likely with the CPU, which is very bad.
A PLC's primary duty is to control the functions of a system using the underlying logic that has been programmed into it. PLCs are used by businesses all over the world to automate their most crucial procedures. A PLC receives data from various sources, including automated data capture points and human input points such as switches and buttons.
PLCs are classified as Relay output, Transistor output, or Triac Output PLCs based on their output. Both AC and DC output devices benefit from the relay output type.