If your usual tools are the Arduino and the Raspberry Pi, you might find it surprising that the industrial world tends to run on Programmable Logic Controllers, or PLCs. You can think of a PLC as a very rugged industrial Arduino, but it’s best not to take that analogy too far. Some PLCs are very simple and some are quite complex, but one thing they do have in common is they are usually programmed using ladder logic. If you’ve ever wanted to learn how to program PLCs — a very marketable job skills in some places — you can now build and simulate ladder logic in your browser. [Garry Shortt] has a video walkthrough of the tool, that you can see below.
If you are used to conventional programming, you may find ladder logic a little frustrating. Originally, it was a documentation tool for relay logic but has grown to handle modern cases. It may actually help you to not think of it so much as a programming language, instead as a tool for drawing relay schematics. Contacts can be normally open or closed and in series or parallel to form AND and OR gates, for example, while coils can activate contacts.
In industry, ladder logic is well understood, and PLCs implement it in real time. It is also often very clear what the ladder is actually doing, more so than trying to read code, especially for people who are not necessarily coders.
Still, you may prefer normal programming. There was a recent post we did about a showdown between Arduino and a PLC. If you read the comments, a lot of people think the playing field favored the PLC, but it is still an interesting comparison. If you want real hardware, there are inexpensive options from the usual China sources and even an open source PLC.
Filed under: Microcontrollers