What are the typical features of the PLC programming language and form

by:Coolmay     2020-07-08

PLC programming language, compared with common computer language has distinct characteristics, it is different in a high-level language, also different with the general assembly language, it should not only meet the easy to write, and to meet the requirements of easy to debug. Currently, there is no one for each manufacturer product can be compatible with the programming language. Products such as mitsubishi company has its own programming language, OMRON company's products has its own language. But no matter what type of PLC,

PLC programming language has the following features:

1. Figure form command structure: program by the graphic expression, instruction is composed of different graphic symbol, is easy to understand and memory. System software developers have the independent operation of industrial control function into a symbolic figure, user these graphics are combined, according to their own needs and fill in the appropriate parameters. In logical operations section, almost all the manufacturers adopt similar to the ladder diagram of control circuit of relay, it is easy to accept. Like Siemens company also USES the flow chart of control system, it used binary logic components graphic symbols to express the control relation, was very straightforward. More complex arithmetic operations, timing, counting and so on, generally refer to ladder diagram or logical component diagram given said, symbolic, though less logic operation part, is also popular with the users

2. Clear variables constant: graphic character is equal to the operation code, regulation the function of operation, the operand filled by the user, such as: K400, T120, etc. PLC of variables and constants and their values range have specific provision, is determined by the product model, please refer to product catalog manual.

3。 Simplify the program structure, PLC program structure is very simple, usually a typical block structure, different piece of complete function, make the program debugging of control functions and control sequence to the entire program has a clear concept.

4。 Simplified application software generation process: the use of assembly language and high-level language program, to complete the edit, compile, and link the three process, and use the programming language, only need to edit a process, the remaining done automatically by the system software, the whole process of editing in the man-machine dialogue, does not require users with advanced software design capabilities.

5。 Improved debugging tool: the assembler, or high level language program debugging, is make editors headaches, and PLC program debugging provides perfect conditions, using the programmer, using PLC and programming on buttons, display and editing, debugging, monitoring, etc. , and with software support, diagnose and debug operation is very simple.

all in all, PLC programming languages are geared to the needs of users, the users are not required to have knowledge of the advanced training, don't need a long time.

PLC programming language in the form of a

this teaching material USES two of the most commonly used programming language, one is the ladder diagram, the second is mnemonic language table. USES the ladder diagram programming, because it is intuitive and easy to understand, but you need a personal computer and the corresponding programming software; The mnemonic form facilitate experiment, because it only need a simple programmer, rather than having to use expensive graphics programmer or computer programming.

although also has some high-grade PLC and computer compatible with the C language, BASIC and special high-level language ( Such as Siemens GRAPH5, mitsubishi MELSAP) And cloth, logic language and general computer compatible assembly language, etc. The programming language, however, each manufacturer can only apply to products of our factory.

programming instructions: instructions are PLC were told what to do, and how to do the code or a symbol. In essence, instruction is just some binary code, this PLC is identical with the ordinary computer. PLC has compiled system at the same time, it can compile some text symbol or graphic symbol into machine code, so the user sees the PLC instruction general writing code rather than machine code, or graphic symbols. Commonly used mnemonic statement in English language ( Available multinational text) Abbreviations and number represents the corresponding instructions. Common graphic symbol or ladder diagram, it is similar to the electrical schematic diagram symbols, easily accepted by electrical workers.

command system: a PLC with the instructions of all referred to as the PLC system. It contains the instructions of how many, each instruction can do something, represents the PLC function and performance. Generally speaking, the PLC controller function is strong, good performance, its instruction system will be rich, what do it. We must make clear before the programming of PLC instruction system

program: an ordered set of PLC controller instruction, PLC run it, can undertake the corresponding work, of course, here refers to the user program of PLC program. User programs generally designed by the user, PLC affiliate does not provide or manufacturer. Language expression program is not intuitive, readability is poor, especially the more complex procedures, more difficult to read, so most programs use ladder diagram to express.

ladder diagram, ladder diagram is through online the trapezoidal diagram of PLC instruction symbols together is the connected graph, used to express the use of PLC instruction and its sequence, it is similar with the electrical schematic diagram. Its online there are two: one for the bus, the other for internal relation line. The internal relation line puts ladder diagram symbol instructions together as a group, the instruction set is of general loading ( LD) Instruction, if necessary after again (with a number of input command LD instructions included) To establish logical condition. Finally for the output class instruction, realize the output control, or for the data control, process control, communication processing and monitoring work instruction, for the corresponding work. Bus is used to connect the instruction set.


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