【Daily Question 20090227】Question: There are 5 types of programming languages

The programming languages for PLCs include the following five: Ladder Diagram language (LD), Instruction List language (IL), Function Block Diagram language (FBD), Sequential Function Chart language (SFC), and Structured Text language (ST)

The user program of a PLC is designed by engineers based on the process control requirements of the control system, using the PLC programming language. In accordance with the industrial control programming language standards established by the International Electrotechnical Commission (IEC1131-3). The programming languages for PLCs include the following five: Ladder Diagram language (LD), Instruction List language (IL), Function Block Diagram language (FBD), Sequential Function Chart language (SFC), and Structured Text language (ST). 1. Ladder Diagram Language (LD) The ladder diagram language is the most commonly used programming language in PLC programming. It is a programming language similar to relay circuits. Since electrical designers are familiar with relay control, the ladder diagram programming language has been widely welcomed and used. The ladder diagram programming language is characterized by its intuitiveness and correspondence to electrical operation schematics ； Consistent with the original relay control, it is easy for electrical designers to master. The difference between the ladder diagram programming language and traditional relay control is that the energy flow in a ladder diagram does not represent actual current, and the relays within it are not real relays; therefore, when using it, it is necessary to treat it differently from the concepts of traditional relay control. 2. Instruction List Language (IL): An instruction list programming language is a mnemonic programming language similar to assembly language; like assembly language, it consists of operation codes and operations. In the absence of a computer, a PLC handheld programmer is suitable for writing user programs. At the same time, instruction list programming languages and ladder diagram programming languages have a one-to-one correspondence, and they can be converted into each other using PLC programming software. 3. Function Block Diagram Language (FBD) The Function Block Diagram Language is a PLC programming language similar to digital logic circuits. Functional block diagrams are used to represent the functions of a module, with different functional modules having distinct functions. Characteristics of the functional block diagram programming language: The feature of this programming language is that it analyzes and understands control schemes in terms of functional blocks, which makes it simple ； Functional modules express functions in graphical form, which is highly intuitive; it is easy for designers with a foundation in digital logic circuits to master such programming ； For control systems of large scale with complex control logic relationships, the functional block diagram enables clear representation of the functional relationships, thereby **reducing** programming and debugging time. 4. Sequential Function Chart Language (SFC): The Sequential Function Chart Language is a programming language designed to meet the needs of sequential logic control. When programming, the process of sequential flow actions is divided into steps and transition conditions; based on these transition conditions, the sequence of functional operations within the control system is determined, allowing the system to act step by step in order. Each step represents a control function task, represented by a box. The box contains the ladder logic used to perform the tasks related to the corresponding control functions. This programming language makes the program structure clear, easy to read and maintain, **reducing the workload of programming and shortening the time required for programming and debugging. Used for situations where the system scale is large and the program relationships are complex. Features of the sequential function chart programming language: it focuses on functions, assigns tasks in accordance with the sequence of functional processes, resulting in a clear structure that facilitates the understanding of user programs ； It avoids the drawback that ladder diagrams or other programming languages cannot handle sequential operations, and it also eliminates the problem of complex and difficult-to-understand program structures resulting from mechanical interlocks when programming sequential operations using ladder diagram language ； The user program scanning time is also **reduced**. 5. Structured Text Language (ST) Structured Text Language is a programming language that uses structured descriptive text to describe programs. It is a programming language similar to high-level languages. In large and medium-sized PLC systems, structured text is commonly used to describe the relationships between various variables in the control system. It is mainly used for writing user programs that are difficult to implement in other programming languages. Structured text programming languages use a computational notation to describe the various arithmetic relationships between different variables in a system, thereby carrying out the desired functions or operations. The structured text programming languages used by most PLC manufacturers are similar to high-level languages such as BASIC, PASCAL, or C, but they have been simplified in terms of statement syntax and the types of statements available for easier use. Features of structured text programming languages: Programming is carried out using high-level languages, enabling the execution of more complex control operations ； Certain knowledge of advanced computer languages and programming skills are required, posing high demands on engineering designers. It has poor intuitiveness and operability. Different models of PLC programming software support different types of the above five programming languages; early PLCs only supported ladder diagram programming language and instruction list programming language. Current PLCs support programming languages such as Ladder Diagram (LD), Structured Text (STL), and Function Block Diagram (FBD). For example, SIMATIC STEP7 MicroWIN V3.2. In the design of PLC control systems, designers are required to not only understand the hardware capabilities of PLCs but also be aware of the types of programming languages that PLCs support.

Ladder Diagram Language (LD), Instruction List Language (IL), Function Block Diagram Language (FBD), Sequential Function Chart Language (SFC) and Structured Text Language (ST)

I think the answers are as follows: 1. Ladder Diagram language (LD) 2. Sequential Function Chart language (SFC) 3. Instruction List language (IL) 4. Function Block Diagram language (FBD) 5. Structured Text language (ST)

Ladder Diagram Language (LD), Instruction List Language (IL), Function Block Diagram Language (FBD), Sequential Function Chart Language (SFC), Structured Text Language (ST)

Including the following five: Ladder Diagram Language (LD), Instruction List Language (IL), Function Block Diagram Language (FBD), Sequential Function Chart Language (SFC), and Structured Text Language (ST)

1. Ladder Diagram Language (LD) 2. Instruction List Language (IL) 3. Function Block Diagram Language (FBD) 4. Sequential Function Chart Language (SFC) 5. Structured Text Language (ST)

Ladder Diagram Language (LD), Instruction List Language (IL), Function Block Diagram Language (FBD), Sequential Function Chart Language (SFC), Structured Text Language (ST)

The standard lists 5 programming languages: FBD, LD, SFC, ST, IL

Ladder Diagram, Instruction List, Function Block Diagram, Sequential Function Chart, Structured Text

Including the following five types: 1. LD language 2. IL language 3. FBD language 4. SFC language 5. ST language

The programmable controller, abbreviated as PC (full English name: Programmable Controller), has gone through several different stages, including the programmable matrix controller PMC, the programmable sequential controller PSC, the programmable logic controller PLC (full English name: Programmable Logic Controller), and finally the programmable controller PC. To distinguish it from personal computers (PCs), the old name of programmable logic controller is still in use today. 　　In the draft PLC standard issued by the International Electrical Committee in 1987, PLC was defined as follows: “A PLC is an electronic device for digital arithmetic operations, designed specifically for use in industrial environments.” It uses programmable memory to store internally instructions for performing operations such as logical operations, sequential operations, timing, counting, and arithmetic calculations, and it can control various types of machinery or production processes through digital or analog inputs and outputs. PLCs and their related peripheral devices should be designed with the principle of enabling easy integration into industrial control systems and easy expansion of their functions. ” Programmable controller: http://baike.baidu.com/view/18980.htm

1. Ladder Diagram Language (LD) 2. Instruction List Language (IL) 3. Function Block Diagram Language (FBD) 4. Sequential Function Chart Language (SFC) 5. Structured Text Language (ST)

FBD and LD are commonly used. SFC, ST, IL

Ladder Diagram Language (LD), Instruction List Language (IL), Function Block Diagram Language (FBD), Sequential Function Chart Language (SFC) and Structured Text Language (ST)

The 5 languages specified in IEC61131-3: 1. Ladder Diagram LD； 2. Instruction Set IL ； 3. Function Block Diagram FBD ； 4. Sequential Function SFC ； 5. Structured Text ST ；

Ladder Diagram Language (LD), Instruction List Language (IL), Function Block Diagram Language (FBD), Sequential Function Chart Language (SFC), and Structured Text Language (ST)

The five specified languages are as follows: 1 Ladder Diagram language (LD), 2 Instruction List language (IL), 3 Function Block Diagram language (FBD), 4 Sequential Function Chart language (SFC), 5 Structured Text language (ST)

FBD, LD, SFC, ST, IL

Ladder Diagram Language (LD), Instruction List Language (IL), Function Block Diagram Language (FBD), Sequential Function Chart Language (SFC) and Structured Text Language (ST)