Relay Ladder Logic

Ladder Diagram or Relay Ladder Logic (RLL) is the fundamental programming language for programmable logic controllers (PLCs). On the other hand, electrical schematics can look a lot like Ladder Diagrams in a vertical way. The solution is to design them as electrical schematics, most individuals learn to draw Ladder Logic Diagrams this way. Although clearly, certain variations persist that we will see below.

To perform logic and control functions is possible to interconnect electromechanical relay. They will act as logic elements in much the same way as digital gates (AND, OR , etc.). Although, the Ladder Diagram is a closely common form of a schematic diagram. It shows the interconnection of relays to perform these functions. In a “Ladder” Diagram, the draw of the two poles of the power source is the vertical rails of a Ladder, with horizontal “rungs” showing the switch contacts, relay contacts, relay coils, and final control elements.
Even so, the problem here is that the electrical control systems and the PLC work in many different ways, so it is difficult to find a general one. Here are the biggest distinctions:

!!!! You could execute (activate) many lines (current paths) at the same time in electrical systems!!!!

  1. The PLC takes a Ladder Logic line (rung).
  2. Executes it.
  3. Moves to the next line.

Introduction to Ladder Logic

Ladder logic is a graphical programming language. This means that instead of text, programming consists of combining different graphical elements which name is Ladder Logic symbols.

One of the clever things about Ladder Logic symbols is that they are similar electrical symbols. Ladder Logic was for people with electrical experience. For example, people who have work with electrical diagrams and schematics.

As in electrical diagrams, Ladder Logic has symbols for contacts and relays called coils in Ladder. The symbols may look a little different from those found in electrical diagrams, but they have almost the same functions.

Example ladder logic symbols.

You can take a look at the IECuino available tools ⚒️ to know more about the online ladder editor.

1 thought on “Relay Ladder Logic”

  1. Pingback: Ladder Logic Basics I - Online Ladder Editor for Arduino - Still Beta 😉

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