Input assembly is used to transmit the input signals from the processor of the PLC to the controller of the PLC. Input assembly includes various switches, operator inputs and pressure sensors. This assembly can be termed as the senses of the PLC which is used to sense different inputs. Different kinds of inputs can be provided to the PLC as per the programming of the PLC. The input of the PLC can be also divided into analog and digital categories. Each category is handled by its own specific class.
Output assembly is used to transmit the executed data from the PLC to the outside world. The outside world can be any application of the PLC. This assembly is called the actuator of the PLC. Outputs from the PLC are received in different forms at the receiving end. The output can be also of analog or digital type depending upon the input type.