Common Types of PLC Programming Languages

Common Types of PLC Programming Languages

It may seem obvious, but when we give instructions to our employees, we use language. We tell them to turn on their equipment after they arrive or clean up an area if there is a mess. We may offer instructions using other forms of communication as well, such as email, signs, or even hand gestures depending on the scenario.

Our CNC systems don’t have vocal cords, hands, or an email address, yet the system’s controller is giving instructions to the rest of the system to mill, drill, or cut. And the language that it uses are programs. Knowing the common types of PLC programming languages will help you choose the right language for your CNC machinery.

Ladder Diagram (LD)

Ladder diagrams are one of the earliest programming languages created back in the days of relay-logic when programs relied on physical switches.

The language itself is a graphic language that mimics a ladder, hence the name. This helps it keep its place as one of the more popular choices of programming languages. The system is incredibly intuitive, and its graphic nature makes it easy for programmers to debug flaws.

Sequential Function Charts (SFC)

Sequential function charts are another good option for people who prefer a visual representation of a program. SFC sets up its code like a flowchart that places the functions in sequential order. This makes it ideal for processes where sequence is the most important part of the operation.

Like ladder logic, it’s relatively simple to debug. However, the syntax can be more complicated than other programming languages.

Function Block Diagram (FBD)

Function block diagrams are more complicated. This program offers the most flexible option for graphic programming languages. Inputs and outputs can be placed anywhere on the sheet, linked in blocks by connection lines. This language works very well for programming that uses motion controls.

While some users find the flexibility of function block diagrams, the ability to put inputs and outputs anywhere makes it easy for the code to get disorganized. That can make it challenging to identify issues when you’re trying to debug it.

Structured Text (ST)

When your code requires massive amounts of calculations, graphic types of programming languages may not capture the calculations well. In these cases, text-based programming languages may work better, especially structured text.

Structured text lists every individual line of code. The complexity can make it easy to make mistakes and difficult to identify those mistakes. However, it does allow for a great degree of flexibility to handle complex codes and transition between different platforms, including java.

Instructional Lists (IL)

Instructional lists are similar to structured text in their format. Both are text-based programming languages, but instructional lists organize the lines with mnemonic codes. This makes the text somewhat easier to read than structured text and helps it to move faster as a program.

Here at Industrial Automations, we want to make sure you have the parts that speak your equipment’s language. That’s why we have thousands of PLC spare parts to fit your business’s needs.