1、附录 Abstract: Programmable controller in the field of industrial control applications, and PLC in the application process, to ensure normal operation should be noted that a series of questions, and give some reasonable suggestions. Key words: PLCIndustrial Control Interference WiringGroundProposal De
2、scription Over the years, programmable logic controller (hereinafter referred to as PLC) from its production to the present, to achieve a connection to the storage logical leap of logic； its function from weak to strong, to achieve a logic control to digital control of progress； its applications fro
3、m small to large, simple controls to achieve a single device to qualified motion control, process control and distributed control across the various tasks. PLC today in dealing with analog, digital computing, human-machine interface and the network have been a substantial increase in the capacity to
4、 become the mainstream of the field of control of industrial control equipment, in all walks of life playing an increasingly important role. PLC application areas Currently, PLC has been widely used in domestic and foreign steel, petroleum, chemical, power, building materials, machinery manufacturin
5、g, automobile, textile, transportation, environmental and cultural entertainment and other industries, the use of mainly divided into the following categories: 1.Binary logic control Replace traditional relay circuit, logic control, sequential control, can be used to control a single device can also
6、 be used for multi-cluster control and automation lines.Such as injection molding machine, printing machine, stapler machine, lathe, grinding machines, packaging lines, plating lines and so on. 2. Industrial Process Control In the industrial production process, there are some, such as temperature, p
7、ressure, flow, level and speed, the amount of continuous change (ie, analog), PLC using the appropriate A / D and D / A converter module, and a variety of control algorithm program to handle analog, complete closed-loop control. PID closed loop control system adjustment is generally used as a condit
8、ioning method was more. Process control in metallurgy, chemical industry, heat treatment, boiler control and so forth have a very wide range of applications 3.Motion Control PLC can be used in a circular motion or linear motion control. Generally use a dedicated motion control module, for example a
9、stepper motor or servo motor driven single-axis or multi-axis position control module, used in a variety of machinery, machine tools, robots, elevators and other occasions. 4.Data Processing PLC with mathematics (including matrix operations, functions, operation, logic operation), data transfer, dat
10、a conversion, sorting, look-up table, bit manipulation functions, you can complete the data collection, analysis and processing. Data processing is generally used, such as paper making, metallurgy, food industry, some of the major control system 5.Communications and networking PLC communication with
11、 the communication between PLC and the PLC and other communications between intelligent devices. Along with the development of factory automation network, the PLC now has communication interface, communication is very convenient. Application features of PLC 1.High reliability, strong anti-interferen
12、ce High reliability is the key to performance of electrical control equipment. PLC as the use of modern large scale integrated circuit technology, using the strict production process, the internal circuits to the advanced anti-jamming technology, with high reliability. Constitute a control system us
13、ing PLC, and the same size compared to relay contactor system, electrical wiring and switch contacts have been reduced to hundreds or even thousands of times, fault also greatly reduced.In addition, PLC hardware failure with self-detection, failure alarm timely information. In the application softwa
14、re, application are also incorporated into the peripheral device fault diagnosis procedure, the system is in addition to PLC circuits and devices other than the access protection fault diagnosis. In this way, the whole system extremely high reliability. 2.Fully furnished, fully functional, applicabi
15、lity PLC to today, has formed a series products of various sizes, can be used for occasions of all sizes of industrial control. In addition to processing other than logic, PLC data, most of computing power has improved, can be used for a variety of digital control in the field. A wide variety of fun
16、ctional units in large numbers, so that penetration to the position of PLC control, temperature control, CNC and other industrial control. Enhanced communication capabilities with PLC and human-machine interface technology, using the PLC control system composed of a variety of very easily. 3. Easy t
17、o learn, well engineering and technical personnel welcome PLC is facing the industrial and mining enterprises in the industrial equipment. It interfaces easily, programming language easily acceptable for engineering and technical personnel. Ladder language, graphic symbols and expressions and relay
18、circuit very close to are not familiar with electronic circuits, computer principles and assembly language do not understand people who engage in industrial control to open the door. 4.System design, the workload is small, easy maintenance, easy to transform PLC logic with memory logic instead of wi
19、ring, greatly reducing the control equipment external wiring, make the control system design and construction of the much shorter period, while routine maintenance is also easier up, even more important is to change the procedures of the same equipment has been changed production process possible. T
20、his is particularly suitable for many varieties, small batch production situations. (1)Installation and wiring Power lines, control lines and power lines and PLC I / O lines should be split wiring, isolation transformer and PLC and I / O should be used between the cable connection Shuangjiao. The PL
21、Cs IO lines and power lines go separate lines, such as to be in the same groove, the separation of bundled communication lines, DC lines, if conditions allow, the best sub-groove alignment, not only will it have the greatest possible distance and can reduce the noise to a minimum. PLC should stay aw
22、ay from strong interference sources such as welding, high-power silicon rectifier devices and large power equipment, not with the high-voltage electrical switch installed in the same cabinet. PLC in the cabinet should stay away from power lines (the distance between the two should be more than 200mm
23、). And PLC cabinets installed within the same inductive load, such as large power relay, contactor coil, arc should be parallel RC circuit. PLC input and output separately from the best alignment, switch and analog should be laid separately. The transmission of analog signals should be shielded cabl
24、e, one end or both ends of the shield should be grounding resistance should be less than the shielding layer 1 / 10. AC output line and DC output lines do not use the same cable, the output line should be far from power lines and power lines, to avoid parallel. (2)I / O wiring terminal Input Connect
25、ion Input wiring generally not too long. But if the environment interfere with small, small voltage drop, the input terminal can be properly longer. Input / output lines can not be used with a cable, input / output lines should be separated. The extent possible, normally open contact form to connect
26、 to the input in the establishment of the ladder and relay the same schematic, easy to read。 Output connection Output wiring is divided into separate output and public output. In different groups, using different types and voltage levels of output voltage. However, output in the same group can only
27、use the same type, the same voltage level of power. As the PLCs output devices are packaged in printed circuit board and connected to the terminal board that if the load short-circuit connecting the output components, printed circuit boards will be burned. With relay output, inductive load borne by
28、the size, will affect the relay service life, hence the use of inductive load shall exercise reasonable choice, or additions isolation relays. PLC may interfere with the output load, so to take measures to control, such as the DC output of the continued flow of control protection, exchange of the ou
29、tput RC snubber circuit, transistors and resistors Triac output bypass the protection. PLC applications need to pay attention to the problems PLC is an automation controls for industrial equipment, generally do not need to take measures, it can be directly used in industrial environments. However, despite the high reliability as mentioned above, strong anti-interference ability, but when the production environment is too harsh, especially strong electromagnetic interference,
