PLC programming language types

According to programmable applications, programming languages can be used in combination, commonly used programming languages:
Ladder diagram programming language
Boolean mnemonic programming language (STL)
Function diagram of programming languages
Function block diagram programming language
Structure statement describes the programming language
Ladder diagram and structure statement describes the programming language
Function diagram and Boolean mnemonic programming language
Boolean mnemonics and structured statement describing programming languages


1, ladder (Ladder Diagram) programming language
Ladder diagram programming languages are ladder diagram symbols to describe a programming language to program. Ladder diagram programming language used, the program takes the form of ladder diagram description. This programming language conditions of causation is used to describe events and results. Each step is a causal relationship. In cascade, and describes the conditions that the event occurred on the left, behind the incident results in.
Ladder diagram programming language is the most commonly used programming languages. It comes from a relay logic control system description. In the field of industrial process control, electrical technicians are familiar with relay logic control technology is, therefore, by this logic control technology development of ladder were welcome, and a wide range of applications.


Ladder diagram programming language features:
(1) corresponding to the electric schematic, intuitive and correspondence;
(2) consistent with the original relay logic control technology, electrical technology, easy to grasp and learn;
(3) with the original relay logic control technology of difference is, energy flow in the ladder diagram (Power FLow) is not a useful current, relays are not within the actual relay, so when needed the original relay logic control technology concepts to be treated;
(4) one by one with the Boolean mnemonic programming language relationship, facilitate mutual conversions and process checks.


2, Boolean mnemonics (Boolean Mnemonic) programming language
Boolean mnemonic programming languages are using Boolean mnemonic to describe a programming language to program. Boolean mnemonic Assembly language is very similar to programming languages and computer, used to express Boolean mnemonic function.
Boolean mnemonic programming language has the following characteristics:
(1) is represented by a mnemonic character manipulation functions, is easy to remember and easy to grasp features;
(2) making up a thread on the keyboard that is represented by a mnemonic, has the characteristic of easy operation, in computer programmingfree design;
(3) corresponding to the ladder one by one. Its basic characteristics and ladder diagram language is similar.


3, the function diagram (Sepuential Function Chart) programming language
“Δ PI core at qiaoqi JI sash constricta scoops pumeiyun timid mold δ PI core at qiaoqi offering defects Fang grow permanent teeth sash flies SAC restored colonization sash constricta scoops Park americium bath k  wall  Yun beat ⒄ method Hu blow SAC restored colonization sash constricta scoops Park americium bath 2 take mold δ PI core at qiaoqi envy took Fang Zhi  Li Portuguese low ring rule  outfitting screen limulus unitary low often  Yong δ amaranth Oboro Zheng  melon low car moutong sacral Shen Xin charm returned twilight  Dan when 构词成分。 recalled scoops forced cough baking tube boy charm cough bi scoops bashing flail system Tomb low ǎ when 构词成分。 Lei sash flies Sam check ど scoops ping figure they resembled ripples Palmetto token bath 9 δ PI core at qiaoqi JI sash constricta scoops Park americium margin milk di Kang led? BR> (1) to function for mainline, structured clear, Ease of understanding and communication of program operations;
(2) for large programs, Division of design, a more flexible program structures, to save programming time and debugging time;
(3) commonly used in large scale school system, the program more complex situations;
(4) only performed step commands and actions are, scan conversion to the active step, thus, the entire program to scan other programs program scanning time significantly shorter.
Function diagram from Petri, Laurentius (Petri) network, because of its graphical expression, can be relatively simple and clear description of concurrent systems all phenomena and complex systems, and system deadlocks, insecurity and other anomalous phenomena analysis and modeling, models can be programmed directly on the basis of, so, get pan application. In recent years, the introduction of programmable controllers and small distributed control system also provides the function diagram is used to describe programming language software. Petri, Laurentius (Petri) some basic concepts of network, when I will have the opportunity to introduce to members to help further understanding of the function diagram.


4, function block diagram (Function Block) programming language
Function block diagram programming language is using function module to module has the function, different functional modules with different functions. It has several inputs and outputs, by way of flexible connections, connected to the other Terminal required, complete the necessary control operations or control functions. Function modules can be divided into different types, in the same type, may also be different for function parameters to functions or applications differ, for example, input the number, the type of input signal, such as the use of different make it different. Because of how soft the function module and function modules and connection to an external terminal, control changes, signal connections replace operation can be easily achieved. Function block diagram programming language features are:
(1) to function as a unit, start from the control function, makes it easier to control analysis and understanding of the programme;
(2) functional module is a graphical method of describing function, it greatly facilitates the design, intuitive staff programming and configuration, better ease of operation;
(3) control larger, controlled a copying system, owing to the control function can be expressed more clearly, therefore, programming and configuration time can be shortened, can also reduce debugging time;
(4) because each function module requires a certain amount of program memory, perform on the function module requires a certain amount of time, so the design language in large and medium sized programmable controller and distributed control system has been introduced only in the programming and configuration.


5, structured statements (Structured Text) describes the programming language
Describes the programming language is a structured statement using a structured description of the phrase to describe a programming language to program. It is a programming language similar to the high-level language. Large programmable logic controller systems, structured statements describing the programming language is often used to describe the relationship between variables in the control system. It is also used for programming and configuration of distributed control systems.
Description of structured statements describe computer programming language statements to describe the system in a variety of various operations relationships between variables, function or operation that you want to complete. Most manufacturers use the statement describing the programming language BASIC language, high-level languages such as PASCAL or c language is similar, but for ease of application, in the statement expression and statement types are simplified.
Structured programming language has the following characteristics:
(1) using high-level programming languages, you can complete some of the more complex control operations;
(2) the need to have some computer programming skills and knowledge of a high-level programming language, the programmer‘s high skill requirements, General Electric technician could not be completed.
(3) poor performance such as intuitive and easy operation;
(4) often used in both modules, some of the other languages, such as implementation of the control functions.
Part of the programmable controller‘s manufacturer provides a simple structured programming languages, like a mnemonic programming language for the program, certain restrictions on the number, at the same time, provides the programmable logic controller interface or presentation of the communication connector and provides extension for user‘s application.

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