The detailed of skill of sound design type selecting of PLC is solved

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When Plc system is designed, should define systematic program above all, next jobs are the design type selecting of PLC. Choose PLC, the specific type of the manufacturer home that basically is affirmatory PLC and PLC. To systematic program the requirement has distributed system, long-range I/O system, still need to consider the requirement of network news report. So specific how should choose PLC? The author thinks to should have the content of the following respects. One, the manufacturer home that PLC produces manufacturer to decide PLC, the familiar degree to different manufacturer PLC and the consistency that design product of habit, form a complete set and technology serve the requirement that basically should consider equipment user, architect the element that waits for a respect. From the dependability consideration of PLC itself, in principle wants the product that is foreign big company only, should not put in the problem with bad dependability. Author individual thinks, generally speaking, to controlling the circumstance of independence equipment or simpler control system, the PLC product of Japan of form a complete set, opposite for sexual value is fairer than having advantage. Requirement of function of news report of larger to systematic dimensions network is the distributed control system of tall, open sex, long-range I/O system, the PLC of Euramerican production has an advantage more on function of network news report. Additional to a few special industries (for example: Metallurgy, tobacco) should choose to there is mature and the outstanding achievement that join movement, reliable PLC system in relevant industry domain. 2, the input is outputted (I/O) the input of PLC of check the number / one of basic parameter that output check the number is PLC. Of the answers to need in order to control equipment place certainly all I/O check the number of I/O check the number add up to according to. Be in usually, the I/O dot of PLC should have proper surplus. Export check the number according to statistical input normally, increase 20 % of 10 % ~ again can expand after surplus, output data of estimation of check the number as the input. When actual order, still need a basis to make the product characteristic of manufacturer PLC, to inputting output check the number undertakes adjustment. 3, capacity of memory capacity memory is but the hardware location bulk that program controller itself can provide, program capacity is the size of the location that project of application of the user in memory uses, because this program capacity is less than memory capacity. Design phase, because the user applies a program to had not woven, accordingly, program capacity is in design phase is sealed, after needing to be debugged in the program, ability knows. To there can be certain estimation to program capacity when design type selecting, the estimation that uses memory capacity normally will replace. The estimation of capacity of PLC memory memory does not have fixed formula, different formula gave out in a lot of document data, substantially is the 10 ~ that measure I/O check the number by the number 15 times, add upper mould to draft 100 times of I/O check the number, the total word that is memory with this number is counted (16 are a word) , press the 25% considerations surplus of this number again additionally. 4, the option that control function should choose to include the character such as operation function, control function, communication function, process designing function, diagnostic function and processing speed. (One) the operation function of simple PLC includes operation function logistic operation, time and computation function; The operation function of common PLC still includes data shift, wait for operation function quite; Function of more complex operation has algebraic operation, number to wait according to conveying; There still are the PID operation that imitate measures and function of other and advanced operation in large PLC. As the occurrence of open system, already had communication function in PLC at present, some products are had correspond with what leave an opportunity, some products are had with parity machine or go up the communication of a machine, some products still have the function that undertakes with factory or intranet data corresponds. When designing type selecting, should ask to set out from what apply actually, reasonable the operation function that chooses place to need. Great majority uses an occasion, need logistic operation and timing computation function only, some application need to data conveys and be compared, when be used at imitate to the quantity detects and be controlled, just use algebraic operation, numeric changeover and PID operation. The operation such as coding and encode needs when returning some wanting that show data. (2) function of control function control includes PID to control operation, before operation of control of compensation of make a present of, ratio control operation, answer to ask to decide according to control. PLC basically is used at be being controlled logically orderly, accordingly, most circumstance often uses odd return circuit or much loop controller solves the control that imitate measures, also use appropriative intelligence to input output unit to fulfil needs control function sometimes, increase the processing speed of PLC and economic memory size. Use PID to control tally of unit, high speed, belt speed to spend compensatory simulation unit, ASC to pile up changeover unit to wait for example. (3) communication function is large and medium-sized PLC system should support a variety of spot bus line and standard communication agreement (like TCP/IP) , the network should manage with the factory when need (TCP/IP) photograph join. Communication agreement should accord with ISO/IEEE communication standard, should be open communication network. The communication interface of PLC system should include serial with collateral communication interface (RS2232C/422A/423/485) , interface of net of aether of RIO communication mouth, industry, commonly used Dcs; Large and medium-sized PLC communication bus line (contain interface equipment and cable) should 1: 1 redundant configuration, communication bus line should accord with international standard, communication distance should satisfy device to ask actually. In the communication network of PLC system, ranking network communication rate should be more than 1Mbps, communication bear is more than 60% . Main form has the communication network of PLC system following a few kinds of forms: 1) PC gives priority to a station, much stage is with model PLC from the station, form network of simple and easy PLC; 2) a PLC gives priority to a station, other it is with model PLC from the station, form network of PLC of type of principal and subordinate; 3) PLC network joins DCS serves as in large DCS through specific network interface child net; 4) special PLC network (the network of special PLC communication of each manufacturer) . PLC connects trustful Wu to reduce CPU, according to the real need that the network comprises, should choose to have different communication function (if nod net of aether of bus line of bit righter, spot, industry) communication processor. (4) process designing function leaves way of line process designing: PLC and process designing implement public a CPU, process designing implement when process designing mode, CPU is process designing only implement provide a service, incorrect spot equipment undertakes controlling. After the process designing that finish, process designing implement switch arrives operation pattern, CPU undertakes controlling to spot equipment, cannot undertake process designing. Means of process designing leaving a line can reduce systematic cost, but use and debug inconvenience. Means of online process designing: CPU and process designing implement have respective CPU, lead plane CPU is in charge of spot control, it is inside cycle of a scanning with process designing implement undertake data is exchanged, process designing implement transmit the program of online work out or data to lead plane, below one scanning is periodic, lead plane with respect to the basis new received order moves. Cost of this kind of means is higher, but the system is debugged and the operation goes to the lavatory, in large and medium-sized PLC middling is used. 5 kinds standardize programming language: Ordinal function pursues (SFC) , echelon pursues (LD) , functional module pursues (FBD) 3 kinds of graphs turn language and statement table (IL) , structural text (ST) language of two kinds of text. Chosen programming language should observe its standard (IEC6113123) , still should support forms of a variety of language process designing at the same time, wait like C, Basic, Pascal, in order to satisfy the control requirement of special control circumstance. (5) the diagnosis that the diagnostic function of diagnostic function PLC includes hardware and software. Hardware diagnoses the breakdown position that determines hardware through the logistic judgement of hardware, software diagnostic one's duty is diagnosed outside mixing, diagnose. Passing software to undertake diagnostic to the function of PLC interior and function is inside diagnose, outside waiting for component information to exchange a function to undertake diagnosing is to the CPU of PLC and exterior input output through software, diagnose. Of the diagnostic function of PLC lose by force, affect pair of operations and the demand that maintain staff technology ability directly, affect mean time to maintenance. (6) processing speed PLC uses scanning means job. From the point of requirement of real time sex, processing speed should have been jumped over more quickly, if signal duration is less than sweep time, criterion PLC is less than scanning this signal, those who cause signal data is missing. Quality of speed of processing of the length that handles speed and user order, CPU, software about. Current, the response of PLC contact fast, rate is high, every binary system dictates executive time is made an appointment with 0.

2 ~ 0.

4 μ S, accordingly can the applied need that adaptive control asks tall, corresponding requirement is fast. Scanning is periodic (processor scanning is periodic) should satisfy: The sweep time of small-sized PLC is more than 0.

5ms/K; Large and medium-sized the sweep time of PLC is more than 0.

2ms/K. 5, the type of PLC type PLC: PLC is whole bodily form and module by structural cent model two kinds. The I/0 check the number of whole PLC is less and relatively fixed, the leeway that chooses because of this user is lesser, use at small-sized control system normally. The delegate of this kind of PLC has: The CPM1A series of company of the S7-200 series of Xi Menzi company, FX series of company of 3 water chestnut, ohmic dragon. Module PLC offers a variety of I/O module to be able to be inserted on PLC substrate receive, convenient user chooses reasonably according to need and configure the I/O check the number that controls a system. Accordingly, the configuration of module PLC is more agile, use system of Yu Dazhong control commonly. For example the CVM1 series of company of the S7-300 series of Xi Menzi company and S7-400 series, Q series of company of 3 water chestnut, ohmic dragon. 6, all sorts of module choose (one) the choice that number of module of digital amount I/O measures an input to output module should consider to use a requirement. Be opposite for example input module, lv of take an examination inputs the application such as the n of signal, transmission distance to ask. Output module also has a lot of sort, for example contact outputs relay model, output of canal of brake of AC120V/23V two-way brilliant, DC24V transistor drive, DC48V transistor drive etc. Normally relay outputs output module to have the price range of cheap, use voltage is wide wait for an advantage, but service life is shorter, noisy should the longer, need when be being used at perceptual load increases time surge draws circuit; Output of canal of two-way brilliant brake module answers time to apply to switch more quickly frequent, circumstance of bear of factor of inductance sex low power, but the price is more expensive, overload ability is poorer. Additional, input output module outputs check the number to be able to divide again according to the input for: At 8 o'clock, at 16 o'clock, wait for norms at 32 o'clock, the foundation wants when the choice real need is reasonable deploy. (2) quantity of imitate of module of imitate quantity I/O inputs module, the input signal type that measures according to imitate can divide for: Voltaic input, voltage input, thermocouple input wait. Voltaic input normally signal grade is 4 ~ 20mA or 0 ~ 20mA; Normally signal grade is voltage input module 0 ~ 10V, - 5V ~ + 5V. OK and compatible voltage or electric current input module of input of some imitate quantity signal. Module of imitate capacity output divides electric profiling to output module and electric flow pattern to output module likewise, the signal that electric current outputs has 0 ~ 20mA, 4 ~ 20mA normally. Voltage output signal has 0 ~ 10V normally, - 10V~+10V. Imitate measures an input to output module, according to the input output connects number of channels to be able to be divided wait for norms for 2 passageways, 4 passageways, 8 passageways. (3) module of functional module function includes communication module, fixed position module, pulse to output module of computation of module, high speed, PID to control module, temperature to control module to wait. The take an examination when choosing PLC leads the possibility of functional module form a complete set, choice function module involves hardware and software two respects. In hardware respect, should consider what functional module can go to the lavatory to join with PLC photograph above all, PLC should have the attachment such as cable of position of relevant join, installation and interface, join. On software, PLC should have corresponding control function, pair of OK and convenient function module undertake process designing. For example the FX series PLC of 3 water chestnut is passed " FROM " and " TO " pair of corresponding function module that the instruction can go to the lavatory undertake controlling. 7, redundant function (one) control is unit and redundant 1, important process is unit: CPU (include memory) reach power source to all answer 1B1 is redundant. 2, the hot equipment that also can choose PLC hardware and hot equipment software to form when need is redundant system, 2 be changed again or 3 change system of redundant fault tolerance to wait again. (2) I/O interface unit is redundant 1, the card of many bits of I/O that dominates return circuit should be configured redundantly. 2, the card of many bits of I/O of main test point can be configured redundantly. 3, the I/O signal that wants according to needing counterpoise, can choose 2 be changed again or the 3 I/O interface that change again are unit. General principle is after PLC model and norms general interest are certain, can decide the basic norms of PLC each component and parameter according to controlling requirement one by one, choose to form the type of module each. When choosing module model, should follow the following principle. (One) when economy chooses PLC, should consider performance/price ratio. When considering economy, should consider to apply at the same time but expansibility, maneuverability, investment yields than waiting for an element, undertake comparative mixing give attention to two or morethings, single out more satisfactory product finally. The input outputs check the number to have immediate effect to the price. Every increase to input output to block an expenses with need to increase certain together. After check the number increases some numerical value, corresponding memory also should increase capacity, frame, mother board accordingly, accordingly, the addition of check the number is chosen to CPU, the choice such as limits of function of memory capacity, control is influential. Mix in estimation when choosing, answer mature, make whole control system has more reasonable performance/price ratio. (2) convenient sex says commonly, as PLC, the module that OK and contented control asks often has a lot of kinds, answer when the choice in order to simplify circuit design, convenient use, reduce exterior control parts of an apparatus to be a principle as far as possible. For example: To inputting module, should first choice is OK as direct as exterior detecting element connective inputs a form, avoid to use interface circuit. To outputting module, should first choice can the output module of direct drive load, reduce the component such as auxiliary relay as far as possible. (3) when versatility undertakes type selecting, the unity that should comprise module each considering PLC and general, avoid module sort overmuch. Be helpful for purchasing not only so, reduce spare parts of machine parts or tools kept in reserve, return the interchangeability that can increase a system to form a part each at the same time, for the design, debug and maintenance is offerred convenient. (4) when compatibility chooses PLC system to comprise module each, answer to consider compatibility adequately. To avoid the problem with occurrence bad compatibility, each manufacturer home of main part that forms PLC system is unfavorable and overmuch. If possible sentence, choose as far as possible same the product of a manufacturer home. CNC Milling CNC Machining