Digital input/outpus - ON/OFF buttons


Digital inputs and outputs i.e. ON/OFF signals are most basic and also most common signal types on PLC controllers. With input signals controller can acquire information from sensors or human operators. For example contact sensors or contactless proximity sensors infor controller that some object is touched or is apparent in range. Based on this data PLC can generate output signal to stop the motor, light up the signal lamp etc. Simple buttons acts as digital inputs and enables to provide human interaction to machine. Following task in in this topic demonstrates how to make simple PLC program to read digital inputs and generate digital outputs.


Learning outcomes

After completing the topic student …   

  • understands the basic program blocks of PLC

  • can handline digital inputs and outputs of PLC

  • is able to set and reset of bits

  • is able to program timers and counters

Suggested readings


  2. Industrial examples:

  3. Video: PLC What it is and how it works,