One, the 20 centuries of development of computer of control of our country industry 40 time end at the beginning of 50 time, the flow industry scope of our country is very little, equipment stale, necessary adjustment basically relies on the simplest measuring instrument table to move by artificial operation. 50 time end at the beginning of 60 time, the sensor that our country development produces, change send implement, adjuster, carry out implement etc, basically can show process state, implementation adjustment intent, final order is carried out implement the adjustment that completes pair of technological process asks. At the beginning of 70 time, the project that our country proper motion develops accuses machine begin to apply at industrial procedure to control, it replaced the meter with original indoor control partly. But because suffer at that time the limitation of electronic parts function, the dependability that labour accuses machine itself is far be inferior to now, labour accuses machine brought control is caused centrally " dangerous " concentration. 70 time end, dispersive model control system (DCS) enters labour to dominate a field, solved " dangerous " centralized problem, still solved a few complex control. DCS can build communication network, for big plant production brings a lot of convenience, but its price is resided all the time do not fall high. At the beginning of 80 time, the bus line with stronger adaptability labour accuses machine (STD) emerge as the times require, the promotion of technology of STD bus line and application, make labour controls the function of machine more aggrandizement. 2, industry but program controller (PLC of of PLC) development trend accuses a of machine as labour, what make automation system in main industry country is basic and electronic-controlled device. It has control convenient, dependability masters high, easily, bulk small, price is appropriate wait for a characteristic. According to statistic, when manufacturer of PLC of this age bound the home makes an appointment with 150, manufacture 300 many variety. Predict 2000, sale is 8.6 billion dollar about, 50% what occupy labour to control machine market share, PLC will accuse in labour main place is had in machine market, maintain the momentum that continues to rise. PLC introduces in 60 time end when our country, use as only the control that disperse measures, its function just receives the operation disperse measure the contactor of output to wait, can finish the earliest only with relay echelon is operated logically. The PLC of new generation has PID adjustment function, its application already measured control to enlarge imitate to measure control domain from switch, apply at the industry such as spaceflight, metallurgy, light industrial, building materials widely. But the challenge that PLC also is facing other industry industry to control a product, each manufacturer is adopting measure to improve a product ceaselessly, is main show: of the following respects? ? . Function of miniature, small-sized PLC enhances a lot of famous PLC manufacturer to be rolled out in succession apparently high speed, high-powered, small-sized, especially the PLC of miniature. The FXOS14 of 3 water chestnut is nodded (8 24VDC input, 6 relay output) , its dimension is 58mm × 89mm only, be more than credit card only a few millimeter, and the function increases somewhat however, make the applied domain of PLC expands to be far from industry of industrial pilot other, wait like surgery of snack hall, hospital, revolving door coming back and car, introduce domestic residence, public place of entertainment and commercial department even. 2.
Compositive change what because control content,development trend increases to complication to be changed with tall difficulty, make PLC to compositive change directional development, PLC and PC compositive, PLC and DCS PLC and PID are compositive, compositive wait, and aggrandizement communication ability and network, it is with PC especially base control product increase rate is the rapiddest. PLC and PC are compositive, be about to the computer, PLC and the person that handle personnel, machine interface is united in wedlock together, make PLC can use the software resource with rich computer, and the module of computational function and PLC accesses data interactively. It is with the PC base control easy process designing and the interest that maintain an user, open architecture provides flexibility, reduce finally cost and improve productivity. 3.
To open sex change PLC is put in serious defect, the architecture of soft, hardware that basically is PLC is close and not be open, the PLC of great majority is network of special bus line, special communication and agreement, although process designing pursues for echelon more, but the configuration of each company, find composition of location, Chinese abhorrent, make all sorts of PLC each other incompatible. International electrician association (IEC) promulgated IEC1131-3 1992 " but the standard of process designing software of program controller " , the standardization that is process designing of each PLC manufacturer levelled road. Development is with PC now base, fall in WINDOWS platform, the new generation that accords with IEC1131-3 international standard opens the PLC of architecture to be in the program. CNC Milling