Basic of PLC

LADDER Logic basic for Beginners

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Ladder Logic programming language is the leading popular programming language in PLC programming. It is an extremely intuitive graphical programming language, easy to learn, easy to program and fix errors

Ladder Logic

Ladder Logic programming language is characterized by looking very similar to electrical relay circuits. So if you know the relay control circuit you will learn Ladder Logic programming very quickly and easily

Therefore, the Ladder Logic programming language is the best visual programming language for PLC.It is constantly being up ranked in the Top most popular programming languages in the world according to IEEE Spectrum

Conditions and Actions

# The Basic Ladder Symbols

  • The Basic Funtion for Ladder

# AND Funtion

When both Input-1 and Input-2 have a logic level of 1, Output = 1


# OR Funtion

When one of the 2 Inputs in the logical state is 1, the Output = 1


# NOT Funtion


# NAND Funtion


# NOR Funtion


# XOR Funtion

  • Because ladder languages ​​are very similar to relay circuits, people who know about electrical circuits can easily switch to PLC programming, here are 2 examples.
Relay > Ladder 1
Relay > Ladder 2
  • The following rules when creating an LAD network:

+ Each LAD network must end with a coil or a box command. Do not end a network with either a comparison command (Compare) or a command to detect a threshold (positive or negative threshold)

+ You cannot create a branch that can result in a signal stream in the opposite direction.

+ You cannot create a branch that could cause a short circuit.

Thank you for reading the opening article about Ladder Logic. In the next article, I will guide you to program the basic commands of Ladder

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