The actions and the conditions can be described in any PLC programming language. Transitions with defined logic conditions.This language is used when programming a process that can be split into several steps. Sequential Function Chart is a graphical programming language that is defined as Preparation of function charts for control systems. The logic is performed by different connection lines between inputs and outputs of the blocks. Each function, even an elementary one, is described by a block with inputs and outputs. The FBD is a graphical programming language. It is difficult to debug a big list of instructions. The downsides of this language are the structure and the syntax. Instruction List makes the program compact and offers a big processing speed. There are also operations that make it possible to jump to some label, as well as to call a function. There are some common operations, such as addition, division, multiplication and subtraction. A program consists of a series of instructions, listed as in an assembly program. Instruction List is a low level language that resembles the assembly language. The disadvantage is that this language is more difficult to debug, in comparison with a graphical language. It is easy to implement complex algorithms and work with mathematical functions. This language gives the possibility to operate with inputs and outputs, using different statements such as for, while, if and case. Structured Text is a high level language, which represents a combination of three programming languages: Basic, Pascal and C. This language is called Ladder Logic, because the programs represent a ladder which has two vertical rails and a series of horizontal rugs in between. Besides contacts and coils there are also some blocks that have functions for working with different types of data. There is also a possibility to read the positive or negative edge of a digital signal. Depending on the logic performed on the inputs, specific outputs (also named coils) are activated. The inputs are applied as normally open or normally closed contacts. It was developed to mimic relay logic, that is why the syntax is very simple. Ladder Logic is the most common language used in PLC programming. Basically, using the information from the inputs, and by applying a specific logic written by the engineer, it configures the outputs in a desired way.Īccording to IEC 61131-3 international standard ( International Electrotechnical Commission), there are 5 programming languages to choose from when writing PLC control programs, two of which are textual and the other three are graphical: In order to perform this functionality, it accepts some input and produces output data. A PLC is a Programmable Logic Controller used to control different manufacturing processes.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |