In recent years, as social development, PLC but program controller got extensive use in industrial production, but its safeguard overhaul method and skill, a lot of electrician are not gotten law, the author works for a long time in manufacturing a gleam of, the maintenance that is engaged in electric equipment is overhauled and supervise the work, to PLC development application and maintenance work to be interested particularly, accumulated the experience of more effective and skill. 1, PLC input and output a small PLC to controlling a complex system neatly, what can see is the indicator light with the input output wiring terminal, corresponding relay that fluctuation staggers two rows and PLC number, resemble having the integrated circuit of 10 several feet together. If any person does not see principle graph overhaul breakdown equipment, can be at a loss what to do, the rate that searchs breakdown will be particularly slow. In view of this kind of circumstance, we are expressed one piece according to scale of electric principle graph case, stick on the console of equipment or control ark, indicate the electric equipment symbol that every PLC input outputs terminal number to answer relatively to it, chinese name, namely the function of each pin shows similar integrated circuit. Had this piece of input to output form, can spread out the overhaul to understanding unit process of cargo bandling or the electrician that are familiar with this equipment echelon graph. But not familiar to those pairs of unit process of cargo bandling, for the electrician that won't see echelon pursue, need again scale a piece of form: PLC input outputs logistic function. This watch explained actually to loop is inputted in major unit process of cargo bandling (spark component, associated component) with output loop (executive component) logistic correspondence concerns. Practice proof if you can use an input adroitly to output corresponding watch and input to output logistic function, overhaul electric breakdown, do not carry blueprint, also can freely easily. 2, judgement of input loop overhaul is pressed some twist, the spacing, circuitry stand or fall that inputs loop, can fall in PLC electrify circumstance (had better be in be not moving condition, in case equipment misoperation) , press by twist (or other input contact) , at this moment terminal of corresponding PLC input dot and public end by short receive, by the PLC of the correspondence that twist place input indicator light shines, explain this is pressed twist it is normal to reach line. The light is not bright, the likelihood is pressed twist bad, circuit contact is undesirable perhaps break a string. If be judged further, by it is good to if be,be twisted, so the pen of a watch that uses avometer, receive PLC to input the public end of end directly, another PLC that contacts a correspondence inputs a dot (afore-mentioned operations should take care, must not come up against 220V or 110V input terminal to go up) . Indicator light is right now bright, show circuit existence trouble. Indicator light is not bright, explain this PLC inputs a dot to already damaged (this circumstance is scarce, general strong report inbreaks be caused by) . 3, output loop overhaul outputs a dot to PLC (here talks about relay only output) , if move oppose to resemble a corresponding indicator light not to shine, fall in moving condition in affirmatory PLC, so the PLC input that shows this movement object outputs logistic function to was not satisfied, input loop to give trouble that is to say, press in front tell, the examination inputs loop. If the indicator light of place correspondence is bright, but the executive component of place correspondence is like electromagnetism a powerful person, contactor not movement, check electromagnetism a powerful person to control power source and insurance first implement, the simplest method, go measuring a corresponding PLC to output the communal terminal of the dot with electrography. Electrography is not bright, the power source breakdown such as fusing of may corresponding fuse. Electrography is bright, showing power source is good, the electromagnetism a powerful person of place correspondence, contactor, route gives trouble. After removing the trouble such as electromagnetism a powerful person, contactor, circuitry, still abnormal, use avometer to express a pen only, the output that receives correspondence directly is communal terminal, another PLC that contacts a correspondence outputs a dot, at this moment electromagnetism a powerful person still not movement, the specification outputs circuit to give trouble. If at this moment movement of electromagnetism a powerful person, so the problem outputs a dot to go up in PLC. Meet sometimes as a result of electrography make a false report, can use analysis of another kind of method, with avometer voltage archives quantity PLC outputs the voltage of dot and public end, voltage is 0 or adjacent 0, explain PLC output point is regular, trouble spot is in periphery. If voltage is taller, explain resistance of this contact contact is too great, already damaged. Additional, do not shine when indicator light, but the movement such as corresponding electromagnetism a powerful person, contactor, because overload or short circuit are burned,this output nods this likelihood prison. Should nod this output at this moment outside wiring is torn open come down, archives of reoccupy avometer resistor goes measuring the resistance that outputs dot and public end, if resistor is lesser, explain this contact is bad already, be like resistor infinity, showing this contact is good, the output indicator light that should be a correspondence is bad already. 4, program logic concludes the PLC sort that often uses on industry now is various, to the PLC of low end, echelon graph dictates very much the same, to in high-end machine, be like S7-300, a lot of programs are written with language watch. Economic echelon plan must have Chinese symbol comment, it is very difficult to be read otherwise, before seeing echelon pursue if can understand equipment technology or unit process of cargo bandling probably, look easier. If undertake electric breakdown is analysed, it is application commonly examine a way instead or say to push a way instead, output corresponding watch according to the input namely, from breakdown the dot finds the output relay of corresponding PLC, begin to examine the logistic impact that satisfies its movement instead. Experience makes clear, examine one department issue, breakdown can eliminate basically, it is not much that because equipment is coinstantaneous,two breakdown that reach above two cases are nodded. 5, PLC oneself breakdown is judged generally speaking, PLC is extremely reliable equipment, give fault rate very low, but as a result of exterior reason, also can cause PLC damage. 5.
The immediateness that power source of a 1 job is 220V switch, its input PLC signal contact two down-lead and the power supply cord that are close to the 220V of switch are common cable of a 4 core, should be close to switch attaint, when electrician changes, the fault common thread tone the PLC of the 0 lines of power source and input is wrong, when bringing about power transmission, burned out 3 PLC input a dot. 5.
Because corrode,2 0 lines discharge transformer of systematic power source and interrupt, bring about receive PLC220V power source to rise 380V, burned out the power source module of PLC bottom, the segregation that 380/220V increased when be being rectified and reform after controls transformer. 5.
The PLC of 3 Xi Menzi S7-200 outputs 1L of public end mark, 2L to wait, working computer expresses for ACL1N, + the person that 24V power source expresses pair of abecedarian for L+M or experience is not worth makes a mistake easily. If the fault regards L+M as terminal of 220V power source, power transmission instant is about to burn out PLC24V power source. According to the experience that the author sums up for a long time, the hardware such as PLC, CPU damages or software runs the probability that make mistake to be almost 0, if PLC input dot is not strong report inbreaks be caused by, also won't damage almost, of PLC output relay often drive a point, short circuit of except periphery load or design are unreasonable, load current exceeds rated range, the life of contact is very long also. Accordingly, we search electric trouble spot, the periphery that should be put in PLC mainly is electric on component, always do not suspect PLC hardware or program to have a problem, equipment of this good to fast maintenance breakdown, fast extensive is resurgent producing is very important, the PLC that talks because of this author place controls the electric corrective maintenance of loop, the key is absent PLC itself, however the periphery in loop of PLC place control is electric component. CNC Milling