I. structure of the programmable controller
1. structure of the PLC include most of the hardware and software. Three–ring between the hardware and control objects:
2. first part: is the operating system, using it to manage hardware resources PLC;
3. the second ring: is the build system, which had two rings of PLC software system.
4. the third ring: are applications that implement user requirements. Block diagram of PLC hardware
II. programming of programmable controller
1. ladder ladder diagrams (LD–Ladder Diagram) method with traditional relay diagram
2. Design is very similar to circuit symbols to express the task is intuitive and easy to understand.
3. the statement form statement form also known as directives form (IL-Instruction List). Or instruction list language. Which is based on RD, OR, AND and NOT … … Logical order for statements such as opcodes, to manipulate operand address or parameters of the programming language. Operation code represents the type function to operate, said where the operation of the operand. This programming methodology, compactness, systematic, but is more abstract, sometimes by using the ladder diagram, and then write the appropriate directive statement input. Relationship between ladder diagram and statement form
4. method of programming language (such as c), with the development of numerical control technology, programmable controller control device has been expanded from single to FMS, CIMS, etc. Programmable controller to process information in addition to discrete signals, analog signals, communication signals, still needs to be done with the upper or lower machine to exchange information. Order is not able to use some information processing implementation and high-speed real-time processing methods must be used. For these reasons, high-level language used by the computer will gradually be introduced into PC applications.
5. control system with other programming flowchart (logic) programming functional block diagram representation of “functional block language“ programming method based on the graphical representation of the “graphic language“ programming method represented by the specified child control and directive statements “structured text language“ programming method logic programming method.