28.1 INTRODUCTION

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This graphical language is part of the IEC 1131-3 standard.

An example is given below.

There are different data types for the connection lines.

Inputs and outputs can be negated by adding a inverting input or output.

The functions in the diagrams are based on the other functions available. The inputs to a function enter on the left of the block, and the outputs of the function emerge from the right.

Some functions can have a variable number of arguments. Here there is a third value input to the add block. This is known as overloading.

The ADD function in the example must always have the same inputs, other functions may have variable numbers of arguments.

The tables of