Rails: vertical lines running down the far most ends of the page. When implementing a ladder logic program in a PLC there are seven basic components that are important to know: Ladder logic also helps troubleshoot code because visually, the flow of logic from the LHS start rail can be seen through the logic symbols and to the RHS end rail.Īs with computers, PLCs operate with binary signals, using 1 or 0 - this type of data is called a boolean. When programming ladder logic in a PLC, the graphic, drag and drop nature of ladder diagrams helps create code quickly. Ladder logic was designed to have the same look as electrical ladder diagrams, but instead, the physical contacts and coils are replaced with memory pieces. Engineers, electricians and students that are already familiar with relay logic found it easy to transition from an electric circuit to ladder logic, compared to other text based programming languages. Ladder logic is the most popular method of PLC programming because it is a graphics based programming language and mimics relay logic. With the advent of PLCs, it was essential to keep similar systems in place, thus ladder logic evolved to become the first PLC programming language. However, relays were expensive and they often failed quickly as the mechanical parts wore out and the electricity used burned away the parts. External devices would also be shown on the diagram, such as pumps and heaters. They were numbered in some fashion, usually top to bottom and left to right like spreadsheet cells.Įach device would be represented by a symbol with their corresponding devices. Relay racks are storage systems that are used for networking and communications equipment, and were popularly used prior to the 2000s. Ladder logic began as a method to document the design and construction of relay racks as used in manufacturing and process control.

Process control is commonly understood as a discipline that uses industrial control systems to achieve consistency and safety during production that could not be achieved manually by humans alone.

To understand the history of ladder logic, let’s begin with a definition of process control.

In this article, we will discuss the history of ladder logic, why it’s popular, ladder programming, and ladder logic basics. Learning ladder logic is basically like learning a new language, but thankfully, if you already have some working knowledge of PLCs, you’ll catch on quickly. If you’re interested in working with PLCs, then you have to know the basics of ladder logic and how important it is to these machines. But what makes it so popular, and what does it take to master the language? Ladder logic is a programming language and one of the first languages that was ever used for PLCs or programmable logic controllers. One of the top 5 most popular types of PLC programming languages is ladder logic.

Plc ladder logic program