Being a visually-based language, it is easy to spot where in a rung/circuit the logic is stuck. One of the big benefits of Ladder Logic is the ease with which one can troubleshoot the logic. However, it is still quite popular and the company I currently work for still uses it, almost exclusively. It should be noted that with PACs now including other languages such as ST, FBD, SFC and IL, Ladder Logic is not the only language that people use for PLCs. Relay control logic was shown on drawings, usually called “ladder diagrams”. What is Ladder Logic?Īs I mentioned here, Ladder Logic was developed to make it intuitive to program PLCs which were replacing much of the hardwired relay logic found in industrial environments. If you haven’t yet read Part 3, you may want to go back and start there to give you an idea of the physical devices and connections that you can control with a PLC Ladder Logic program (you may want to read Part 1 and Part 2 even before that!). In part 3, we discussed the different types of PLC I/O and some of the applications they may used in.

My goal in this final part of the “Beginner’s PLC Overview” series is to help YOU to understand the basics of Ladder Logic so you can start using your knowledge of PLC programming as soon as possible to help you get that pay raise, new job or just help you expand your knowledge so you can be a more valuable player! Plus, this stuff is actually pretty fun! But, before we get in to Ladder Logic, let’s do a quick review. This is what I’ve done almost daily for my job for the past several years. Specifically programming PLCs with Ladder Logic. You may become nerdy programming PLCs, but once you get into it, you won’t care This post is about programming PLCs. But PLC programmers are nerdy in a different way. I usually try to explain that programming PLCs is different than typical computer programming and how PLCs are used to automate industrial equipment using a graphical-based programming language called Ladder Logic and how I create programs to automate electrical back-up generators and switchgear…then when their eyes begin to glaze over…I realize…I am a nerd after all. Most people picture the stereotypical programmer pounding out miles and miles of a text-based language like C++, Java or HTML (dare I say a nerdy?).

If they are curious enough to ask more, I usually tell them that I do some control system design and a LOT of programming.

When people ask me what I do, I usually say something like “I work as an engineer for an electrical company”. This is what I've done almost daily for my job for the past several years.Ī Beginner's PLC Overview, Part 4 of 4: PLC Ladder Logic You may become nerdy programming PLCs, but once you get into it, you won't care.

Plc ladder logic program