PLC from the basic to let you know it,plc cpu modules

PLC is a programmable logic controller, mainly used for the logic control, which is composed of a host and an input / output unit. The input and output is the main switch signal, programmable logic controller manufacturer has now developed a simulation signal; the main principle is to accept the input signal to the controller, according to certain logical relationship, the operation on the controller, and the output to the output unit.

In the user view, a detailed analysis of the internal circuit of CPU is not necessary, but the working mechanism of the various parts or should have the enough understanding. Control the CPU controller CPU, plc digital input module  ,explaining and executing command which reads the instruction.

Plc cpu

Since the 1960s, the United States launched a programmable logic controller (Programmable Logic Controller, PLC) to replace the traditional relay control system, PLC has been rapid development,cpu module plc has been widely used around the world. Meanwhile, the function of the PLC is also improved. With computer technology, signal processing technology, control technology continues to develop network technology and the continuous improvement of user requirements, PLC increased the analog processing and motion control functions on the basis of the amount of processing on the switch. Today's modular plc is no longer limited logic control, motion control, process control and other fields also play a very important role.
Programmable logic controllers initially only logic control circuit function, so was named the programmable logic controller, and later with the continuous development of these original features simple computer module already includes logic control, timing control, analog control Many of the features, such as multi-machine communication, the name was changed to the PLC (Programmable Controller), but because plc cpu modules is also shorthand for PC and PC (Personal Computer) shorthand for conflict, but also as a result of many years of usage, people or programmable logic controllers often use this title, and the term is still used in the acronym PLC.

Cpu modules plc

plc cpu module having a microprocessor digital electronic devices for digital logic controller automation and control, control commands can be loaded at any time within the memory storage and execution. By an internal programmable controller CPU, instruction and data memory, input and output units, power modules, modular plc, combined into a modular unit.
Widely used in the current field of industrial control. Prior to the programmable logic controller appears generally to be used hundreds of relays and automation systems in order to form a counter with the same functionality, but now, after the programming of simple programmable logic controller module has basically replaced these large devices. programmable plc controller system program is generally at the factory initialization is complete, users can edit their own according to their own needs appropriate user program to meet different requirements for automated production.

Plc cpu modules

module plc is the control center of the system, users will be prepared to complete the program is downloaded to the CPU module, plc cpu module starts execution of the user program in a circular manner, each cycle should be read into the process information, logical calculations, the output result of the operation, but also the timing set by the user or the time to deal with communications, high-speed counting, event interrupts the process.
PLC control system, Programmable Logic Controller, programmable logic controllers, a digital computing operation of electronic systems, designed for use in industrial environments and design. cpu modules plcuses a programmable memory for its internal storage procedures, the implementation of logical, sequential control, timing, user-oriented counting and arithmetic operations such instruction, and through digital or analog input / output control of various types of machinery or the production process. Is the core of industrial control.

What is the reason plc cpu modules

(1) We live with analog instruments, is the pressure, level, temperature and other signals into 1-5V ,4-20mA ( there are other signals , such as 0-10V ,0-5V , etc. ) and then to the PLC processed .
2.PLC not know the size of the specific  Nanda Programmable Output Module voltage or current signal .
So, we use a number to indicate its size, then tell PLC, PLC in order to know the voltage and current signals input specifically how much.
For example , we measured the temperature is now 20 degrees ( range 0-50 degrees , the output range is 1-5V), a temperature sensor generates a voltage value at that time is (5-1) * 20/50 = 1.6V ( instrument characteristics must be linear so it can be counted ) . After the PLC analog input module receives input of 1.6V , which will be converted into a digital value. For Nanda digital input module  example , the resolution we are using the analog input module is 0-4000 of the corresponding 1-5V . Well , 2.0V should correspond ( 4000-0 ) / ( 5-1 ) * 1.6 = 1600. That is , PLC , after reading the analog input module to its 1600 figures will be able to know it , from the temperature sensor to sensor temperature is 20 degrees

plc cpu machine control technologies more economic sense

Vertical machines require a higher degree of automation is a mechanical and electrical equipment , generally used in the  Nanda Plc logic controllers metallurgical industry , car manufacturing all kinds of large workpieces ; it usually uses electronic control system failure rate relay logic control, equipment , long maintenance cycle . With the advancement of technology, this type of control system has shown a growing number of drawbacks. In recent years, PLC automatic control machines in industrial applications more widely , it is out of the control of the comprehensive advantages in performance , group, machine cycles and hardware costs and other aspects of the performance of other industrial products are difficult to compare . If PLC control technology for these systems to implement reform , the universal technical and economic significance.
    Choose a plan
    Original equipment for manual operation , according to the department's recommendation to maintain the transformation of the Nanda Plc controller manufacturers  former equipment man-machine interface in the transformation of the original program , which can effectively reduce the misuse of equipment personnel , the equipment does not cause the accident rate in the post- transformation increased.
Workbench transmission system relies on hydraulic unit solenoid valve to achieve, constantly changing the transmission ratio by mechanical transmission components , to achieve the purpose of changing the speed of the table . Its variable speed operation is quite complicated , we must let the host parking , selected speed , micro gear back together again Guadang bite , and finally restart. According to the site load calculation and theoretical analysis, the way to retain the main drag .

Different analysis plc cpu control and microprocessor controlled

 PLC is actually a set of ready microcontroller ( MCU wide range of oh ) system .
PLC ladder you can be understood as a compilation of calculators with the same language is a programming language , but a different range ! But common practice by the PLC ladder software to convert your C or assembly language ( used by the PLC the CPU determines ) , then use the assembler or  Nanda Plc controller manufacturers C compiler system compiled into machine code ! PLC is running just a few yards of it . ladder only allows users to more easily use it.
 Similarly the MCS-51 course also be used for making PLC , just eight CPU in some advanced applications such as: a large number of operations ( including floating point ) , embedded systems ( our equipment is slow, but the main logic control , but points many Oh , 128 I / O too ! ! ) , but also use ladder programming , we compile our ladder into KEIL C51 reuse of C51. you do not notice the choice of different models of the PLC the CPU you ! ! course, you can direct the development of single-chip control systems, but very demanding for the developer (not the general level capable of ) , long development cycles, high costs ( for some large decency you need to do a little experiment , printing board requires a substantial amount of money , you can say you use Nanda china industrial automation plc  the simulator , using experimental board to develop, but I want to tell you , do you just verify the feasibility of the hardware and software , does not mean you can use in industry control systems, industrial control systems because the requirements are very high anti-interference , stable first , rather than the performance of the first , so you must constantly test the circuit board design , improvement ) when you solve these problems, you will find that you have to do with a PLC , of course, easy to use if you need someone to be able to use the software you'll need a set , so you may not need to tell others about your circuit ( you can not tell anyone ) .