Low-cost automation (LCA) originated in the first industrial revolution, initially called "easy automation." After the Second World War, due to the restoration of industrial needs, started using a simple automatic control device consisting of relays. The 1950s and 1960s saw the emergence of low-cost automation systems using contactless logic controllers, feedback controllers, or a combination of both; in the 1970s low-cost automation was defined as the application of mechanical, pneumatic, liquid Electric, electronic and optoelectronic technologies to create an automatic device or system with simple structure, low price, easy to use, good quality and quick response, so as to meet the needs of many small and medium-sized industrial enterprises. Since the 1980s, due to the popularization and promotion of microcomputers, new low-cost automation systems with single-chip microcomputer, single-chip microcomputer and embedded system as the core have emerged. In this case, the usual automation system is composed of sequence controller, feedback controller, programmable logic controller (PLC), DCS or microcomputer, local area network, server, workstation and the like with detection switch, sensor or actuator High cost performance ILCA system. At present, LCA system has been widely used in metallurgy, chemical industry, machinery manufacturing, textile, printing and publishing, mining, agriculture, forestry, fisheries, construction, commerce and transportation industries, and achieved significant benefits.
The usual system design should not only advanced system, high degree of automation, but also to ensure that investment as low as possible. In order to solve this contradiction, we must consider various factors synthetically and follow the following design principles on the premise of keeping the investment cost as low as possible.
(1) to meet the needs of the principle: to meet the user requirements for product functionality and automation as the central task of system design.
(2) The principle of reliability: the ability to perform a certain function without any problem under specified conditions and within the prescribed time.
(3) The minimum system principle: Consider to meet the requirements of the premise, with the most simple hardware, software, the most economical way to form the system, the system hardware and software redundancy features minimum.
(4) matching principle: the system requires that the various components of the function and level as close as possible, the level of mutual matching, in order to function fully utilized.
(5) The principle of standardization, serialization and generalization: As far as possible, standardization, serialization, generalization products or mature components or subsystems that have been used should be used for system component selection. As far as possible, the control section uses dedicated modules, serialized controllers and bus modules. In order to reduce development costs, shorten the development cycle, enhance anti-interference ability and improve maintenance conditions.
(6) The principle of advancement: In the premise of meeting the economic performance, new technologies and methods should be adopted where possible to make full use of the achievements already made by the society. Such as the development of mature new technologies, new processes and new components, the original will tend to make the structure more simple, more powerful, more reliable, smaller and lighter weight, operation and maintenance easier.