✅ C'mon over to https://realpars.com/ where you can learn PLC programming faster and easier than you ever thought possible! ============================= ✅ Check out the full blog post over at https://realpars.com/ladder-logic-vs-function-block-diagrams/ ============================= Today you will learn the difference between function block diagrams and ladder logic. Specifically what they are and when do we use them when programming PLCs. Most PLC manufacturers around the world still support ladder logic programming. However, some have been moving towards function block programming. Let’s take a look at some of the similarities and differences. Ladder logic is pretty well “the universal programming language” of PLCs. As I mentioned earlier it has been around for decades and is pretty well understood by most technicians and engineers alike. It is named Ladder Logic because it quite literally looks like a ladder. The vertical lines are referred to as the power rails. The horizontal lines that our programming bits are located on are rungs, just like on a ladder. It is read from top to bottom and left to right. Function block diagrams can essentially convert several lines of ladder logic into boxes. In the middle of the function block will be a symbol or text, labeling the function block. This will describe the actual function of the block. There can be one or several inputs and an output for each function block. Those function blocks can be inputs to other function blocks as well. Just like ladder logic, function block diagrams should be read left to right, top to bottom. In a sense, this format can make it easier for a technician troubleshooting a machine see what is happening to the machine. Let’s look at an “AND” function block first. If you are unfamiliar with “AND” Logic, it is actually pretty simple. Basically, you need at least two inputs energized to turn on or energize its output. I like to think of it as you need this input, and, that input to turn on the output. In ladder logic, it would look like a series circuit like this. In a function block diagram, the entire rung is replaced by this box or block. Many industrial machine use “AND” logic. A large metal Press Brake uses “AND” logic for its controls. The operator must push two buttons at the same time. This energizes the output of the “AND” logic. This allows the cylinders to be activated and bend the metal. Another common function used is the “OR” logic function block. This is like the opposite of “AND” logic. With an “OR” function block, you would energize this input, or, that input to energize the output. In ladder logic, it would look like a parallel circuit like this. Machines may use “OR” logic when there are more than one set of controls to operate the machine. Conveyor belts can utilize this programming. They will commonly have the “Start” and “Stop” buttons located near the conveyor. They can also have a start and stop button at another location in order to start the conveyor remotely. ============================= Missed our most recent videos? Watch them here: https://realpars.com/sensor-calibration/ https://realpars.com/ethernet/ https://realpars.com/fieldbus/ ============================= To stay up to date with our last videos and more lessons, make sure to subscribe to this YouTube channel: http://goo.gl/Y6DRiN ============================= TWEET THIS VIDEO https://ctt.ac/_fxVJ ============================= Like us on Facebook: https://www.facebook.com/therealpars/ Follow us on Twitter: https://twitter.com/realpars Follow us on LinkedIn https://www.linkedin.com/company/realpars #RealPars