Ladder logic (also called ladder diagram or LD) is a
programming language used to program PLCs (programmable logic
controllers). It is a graphical PLC programming language that uses
symbols to represent logical operations. Ladder logic is composed of
logical steps, forming what looks like a ladder-hence the name "ladder
logic".
Ladder logic is mainly used for bit logic operations, but it can also
scale PLC analog inputs. In more advanced PLC programs and SCADA system
programming, even simple bit logic operations are beneficial.
The person or organization that sets the standard for ladder logic is
PLCOpen. Ladder logic is not only a programming language for PLCs. It is
one of the standardized PLC programming languages. This just means that
ladder logic is described in the standard. This standard is called IEC
61131-3. But for now, the only thing you need to know is that there is a
standard to describe this programming language.
