Summarize PLC, ESD, SIS, DCS distinction

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PLC Programmable Logic Controller, regard the control of whole set of equipment as plan normally, e.g. vacuum, liquid waste, collect outfit, compressor becomes the system of one individual department oneself etc. Their characteristic often is not to ask a lot of imitate measure control, to the number the quantity dominates very effective, convenient, reliable, economy. Normally as DCS child site, facilitating surveillance. ESD Emergencyshutdown System is urgent jockey system. SIS Safety Interlockingsystem (Safetyinstrument Syetem) . Safe and interlocking system, the individual thinks this is different manufacturer to safe system call a law to differ, return some to call Safety Manager. This kind of system often is used at the tall danger industry such as petrifaction. The feature that involves commonly is not very much, because once the movement is full-court,jockey, it is the lowermost line of defence with safe safeguard of sacrificial production benefit. SM needs to have SIS attestation, normally grade is petrifaction industry SIL3. Till DCS Distributed Control System is current, its biggest characteristic still is PID control, have the aid of its powerful communication function, it is integrated factory the system of all automation equipment, measure what DCS uses at producing a course continuously, management of groovy control, operation control, those who assure to produce device is smooth move; SIS runs a state with what produce device at surveillance, unusual to appearing operating mode undertakes quickly handling, make the harm falls lowest, make personnel and manufacturing unit are in safe condition; DCS is dynamic system, it is successive to process variable from beginning to end undertake detecting, operation and control, have dynamic control to producing a course, ensure the quality of the product and crop; SIS is static system, when normal operating mode, it is surveillant from beginning to end those who produce device move, systematic output is changeless, do not produce an effect to producing a course, when be not normal operating mode to fall, it will according to beforehand the design has logistic operation, implementation production unit is safe interlocking or jockey; SIS asks on dependability, usability than DCS stricter, IEC61508, IEC61511, ISAS84.

01, in the standard such as SH/T3018, recommend SIS and setting of DCS hardware independence. The PID picture that I see shows, the logistic control of the logistic control of ESD and PLC is different, SIS logistic blueprint is discharge shows, FT is the flow meter of field assembly, FI15101 is show inside DCS, flow is high call the police; DCS logic is discharge adjustment control, control valve and flowmeter installation are in the spot, the drives degree of control discharge volume of valve is carried in computer; DCS accuses what the industry says again to be system of distributing center control oneself in home. It is one controls what class and process monitoring class comprise to be all of multistage computer science department of ligament with communication network by the process, integrated the computer, communication, show and control technology waiting for 4C, its are basic the thought is dispersive control, concentration operation, manage by different levels, configuration is agile and configuration is convenient. The operation uses the computer to operate a station, pass network and controller join, collect manufacturing data, relay operation directive. Accordingly, the main characteristic end of DCS is a word is: Control centralized government dispersedly. ESD -- urgent jockey system. ESD is urgent jockey the system asks according to safe and independent principle, independent at system of DCS distributing center control, DCS of prep above of its safety level. Below normal circumstance, ESD system is in a static state, do not need factitious interpose. As safe protection system, override on manufacturing process control, real time is online the security of monitoring and warning device. When should producing device occurrence emergency only, do not need to pass DCS system, and give out protection by ESD directly interlocking signal, undertake safe protection to spot equipment, avoid danger to diffuse cause huge loss. Why should install ESD system independently? Function of general of course and safe interlocking protection also can come true by DCS. But to more large-scale urgent jockey the system should part according to safe and independent principle and DCS setting, such doing basically have reason of the following respects: (1) reduce control function and safe function at the same time the probability of invalidation, also won't endanger; of safe protection system when safeguarding DCS part breakdown (2) to large plant or equipment of tool of a favourable turn coming back character, urgent jockey it is good that the system answers speed to be jumped over more quickly. This is helpful for protecting facility, avoid an accident to expand; Be helpful for record of resolution accident reason. And DCS handles a large number of processes to monitor information, accordingly its answer speed to be made very fast hard; (3) DCS system is process control system, it is dynamic, need artificial and frequent interpose, this causes factitious misoperation likely; And ESD is a static state, do not need factitious interpose, such setting ESD can avoid factitious misoperation. Of the function of SIS system and ESD basic and same, just want system of prep above ESD on degree of safety, the function that some ESD cannot realize can be above SIS implementation PLC logic is the spot have measure lukewarm place, temperature shows, control and call the police high. CNC Milling CNC Machining