Programmable logic controller文档格式.docx

1、With more and more manufacturers involved in the companys production and development, PLC function expand rapidly, programming language also great rich, this is the development of every new thing must go through the process, also various manufacturers tend to develop their own ladder logic language

2、（for a PLC programming language）. This complex PLC language can not applicable to all types of equipment. However, with the other computer languages like, once this ladder language has been widely used, then the language being used in most of the equipment on the possibility is big, most of the syst

3、em designers will find production of a particular manufacturer of products for the writing system.It should be noted that the programmable logic controller is often referred to as PLC or programmable controller. Although the term programmable logic controller has been widely accepted, it is not like

4、 the abbreviation personal computer, because the abbreviation usually refers to the personal computer used. In this article we will see that PLC does not mean personal computer.Can be programmable controller is the personal computer users as free many configuration options, as personal computers sel

5、ected which is better some completely rely on their own experience, as a controller of a lot of setup options to good control it made him work needs to rely on their own experience.。Modular PLC including the system components are:1 processorProcessor （sometimes referred to as CPU） is a program of th

6、e central processor can execute, which is full of the module with a number of specific features, these features some processing more complex mathematical operations and some of the PID control loop and programmable command processor is composed of a micro processor, a system memory, serial communica

7、tion port and printer, PLC LAN links and external programming equipment system through the I / O port supply.2 ArchitectureGenerally, the metal frame and the printed circuit board are connected with the PLC input and output module and the processor, and the number of the mounting frames required for

8、 the system is realized according to the specified module. The assembly frame provides data and power through the motherboard and the module connection processor. Without power supply structure to preserve the modular power supply, the processor of the system is independently installed and the cable

9、 rack are connected together, frame assembly can is mounted directly to the panel, or can be installed in the standard width of 19 and multiple mounting frame between is linked to ensure that adapt to the large number of I / O module in the whole system.3 input and output modulesThe input and output

10、 （I / O） modules are connected to a particular application program based on the specified input and output signals, which can be divided into discrete categories, analog high-speed counters or register types.Discrete I / O modules are generally able to 8-bit or 16 bit data processing, in some cases,

11、 switch input and output module is specified as an input or output, but manufacturers generally provide a free allocation of inputs and outputs can be cured within the same module.Analog input and output module is feasible and applicable to the expected resolution and voltage or current range, these

12、 have become the general discrete input or output module, some manufacturers between the same module provides analog input and output, to simulate the PLC can also be accepted directly thermocouple temperature measurement and monitoring.Pulse input to PLC can be accepted using high speed countermodu

13、le. This module can be used to measure the frequency of the input signal from the tachometer or frequency generator. These modules can also count the incoming pulses if required. In general, both the frequency and count of the same module, if both are required in the application.The register input a

14、nd output modules transmit information from 16 or 8 bits, and from a programmable controller. These words are usually numbers （BCD code or binary） which are the input data from the encoder switch or encoder system to be generated by the PLC output display device4, power supplyThe specified power dep

15、ends on the manufacturers programmable controller used in the application. As mentioned above, in some cases, the power supply to provide the required power of the system as a part of the processor module. If the power supply is a separate module, it must be able to provide a greater capacity than t

16、he sum of all the currents needed for the other modules. For the internal processor module of power supply system, may have some modules, in the system, much power, rather than from the processor, because voltage or current requirements, only through the addition of a power supply. This is generally

17、 true if the analog or external communication module, as these requirements of the DC power supply, in the case of the analog module, must be well regulated.5, programming unitThe programming unit allows the engineer or technical personnel to enter and edit the program execution. In its simplest for

18、m, it can be a handheld device that shows the steps or functions of the input and display devices （light emitting diodes or liquid crystal displays） to the keyboard input program, as shown in fig. More advanced systems use a single personal computer, which allows programmers to write, view, edit, an

19、d download the program into a programmable controller. This is achieved by the manufacturer with proprietary software available from the programmable controller. The software also allows the programmer or engineer to monitor the program as it is running the program. With this monitoring system, such

20、 as internal coils, registers, timers and other items that are not visible externally can be monitored to determine the correct operation. In addition, the internal register data can be changed, if required to fine tune the program operation. This may be advantageous when debugging a program. Commun

21、ication with the systems programmable controller is a cable connected to a particular programming port on the controller. Connected to personal computers can be installed through a serial port or from a special card.Programmable controller is a kind of special computer. Because it is a computer, it

22、has all the basic components of a computer, a central processing unit, memory, input interface and output interface. The central processing unit （CPU） is an important part of programmable logic controller （PLC） control. It can explain the same procedures and commands directly from memory and behavio

23、r to those commands. This unit in the current programmable logic controller （PLC） is a microprocessor based system. Processor module of central processing unit （CPU） in system module.Memory systems are usually of two types, read-only memory and random access memory. ROMs memory contains program info

24、rmation that allows the central processor to interpret and act on the ladder logic program stored in the RAM store. RAM storage is usually removed in order not to lose the power of the ladder programming system. The battery can be a standard type of dry battery charge. Now the programmable controller （PLC） unit with electrically programmable