Practical Tips and Techniques
Proximity (Capacitive, Inductive), Photo electric (Thru beam, Retro Reflective, Diffuse), Ultrasonic, etc. Sensors can be either discrete (On/Off) or Analog outputs.
We will create a simple and inexpensive analog voltage tester for a PLC using a potentiometer and a 9VDC battery. The potentiometer will be 5K ohms. This should be enough impedance for most analog inputs of the programmable logic controller. (PLC) Voltage impedance for analog voltage inputs is in the megaohm range where the current … Read more
We will now look at the parts of a PLC system. When I was in school PLCs were just in their infancy. We were taught that the PLC consisted of the central processing unit (CPU), analog and digital inputs, and outputs. Everything was programmed with dedicated handheld devices and/or software devices on specialized hardware. We … Read more
We will look at a PLC basic tutorial of a paint spraying station. Following the five steps to program development, this PLC programming example should fully explain the procedure for developing the PLC program logic. Ladder logic will be our PLC programming language. We will use the Do-more Designer software, which comes with a simulator. … Read more
We apply the five steps of PLC development to a plc shift register example. This PLC programming example will use a shift register to reject a product on a conveyor. When programming a PLC, you need to track what has previously happened. Shift registers allow you to do just that. We will look at a … Read more
This post is a further follow-up from my original ‘Here’s a Quick Way to Understand PLC Inputs and Outputs.’ There are two different kinds of PLC outputs, Discrete and analog. Discrete outputs are either ‘ON’ or ‘OFF’; 1 or 0. You can think of them as a single light bulb. Analog outputs have a range … Read more
This post is a further follow-up from my original ‘Here’s a Quick Way to Understand PLC Inputs and Outputs.’ There are two different kinds of PLC inputs, Discrete and analog. Discrete inputs are either ‘ON’ or ‘OFF’; 1 or 0. You can think of them as a single switch. Analog inputs have a range to … Read more
