English (UK) 
简体中文 Sudden equipment shutdown?PLC red light? Do not panic! The old driver hand in hand to teach you "pulse treatment"!
Just entered the line of brothers may have encountered such scenes: production line rumbling round, magnetic separator suddenly "nest", PLC panel a bunch of lights flashing, the master rushed up to a meal on the operation of the repair, but they are full of question marks ... Today we will break open the rubbing, talk about magnetic separation equipment PLC failure how to quickly! Fixed--Remember, you're not tinkering with code, you're talking to a machine!
I. Daily maintenance: don't wait until it breaks down to shoot your leg
This PLC stuff is like a car, regular maintenance is ten times more important than fixing faults!Newbies are most likely to overlook these three points:
- Keep an eye on the battery voltage.: CPU battery dropped below 3V? Change it quickly! Otherwise the programme will be gone when you say it's gone.
- Dust is the enemy.: Monthly takeCompressed air tank blowing control cabinet, dust builds up and shorts out. Don't ask me how I know.
- Even the screws have become fine.Listen for any "clattering" noises. The vibration may have loosened the wiring screws.One turn of the spanner.It works better than anything.
give me a chestnut: A mine PLC old crash, finally found that the cabinet top cooling holes were paste the death of the mineral powder, clear immediately after the stable as a dog.
Second, the fault of quick judgement: look at the lights to know where the problem is
The PLC panel light is its "expression", reading it can save two hours:
| fault phenomenon | Most likely cause | 5-minute self-help method |
|---|---|---|
| Power light off | External power failure/blown fuse | Measure the socket voltage → check the insurance → change the power module |
| The RUN light is blinking wildly. | Programs running away/memory errors | Restart the PLC → recharge the backup programme |
| Input light on but no response | Poor terminal contact/internal burn point | Multimeter measurement of terminal voltage → Shorting test |
| Output jumps wildly | Electromagnetic interference/grounding failure | Sleeve magnetic ring→Check ground resistance <4Ω |
👉 Tears of blood:.Don't believe in the "reset cure"!Repeated resets at a plant resulted in a complete burn through of the module and $80,000 in damages.
Three, diagnosis of the four axes: from rookie to veteran of the road to go through
Q: A teacher can tell the point of failure by touching it twice, is it metaphysical?
A: People use this combo:
- feel for sth.: CPU heating over 60°C? Cooling fan quasi hanging;
- look at sth twice: Input and output indicators do not match the action of the field device?The line is probably broken..;
- hear what sb says: Smells like mush? Quick disconnect!Output module or cable is burnt.;
- tetraplegic hearing: Relay not clicking? Either the coil is burnt or the PLC is not sending commands.
Complicated faults? Use this trick to "move the world around".::
suspecting that there is a problem with any of the modules.Unplug it and plug it in.(Same model only!) . For example, if the input modules are all out of order and a new one is instantly good - congrats, chop your hand off and buy new.
IV. High-frequency fatal triple question (with solutions)
Q1：The touch screen shows "communication timeout", what should I do if I am in a hurry?
- Kick the network cable connector first (don't really kick it! Re-plug)
- Check PLC's and HMI'sConsistency in baud rate(9600 or 19200?)
- Ultimate solution: reboot the switch → reset IP address
Q2: Magnetic field strength is high and low, ore sorting into a lottery?
- Dirty Hall sensor.: Take an alcohol pad and wipe the probe
- The PID parameters have drifted.: Adjust these three numbers (proportional for speed of response, integral for error cancellation, and differential for overshoot).
- High current fluctuation: Check the trigger board of the thyristor rectifier cabinet
Q3: Should I run to the scene if I call the police in the middle of the night for a "temperature overrun"?
- Remote viewing of the HMI.Coil over 60℃ forced shutdownIt's a protection mechanism.
- Self-check three steps: enough water pressure? Cooling pipe plugged or not? Does the fan turn or not?
- Temporary life-saving: Cutting current in manual mode to preserve production
Fifth, money can not buy the voice of experience
After ten years in this business, I've learnt one thing.PLC failures are 80% external!
- Sensor soaking?Adding a waterproof box is better than changing the module.;
- Big motors pumping when the PLC is on?Separate conduits for power and signal lines.;
- Total burn output points?Parallel interrupters on relaysThe contact life is doubled.
Dump the big truth at the end.Don't be dead set on high end technology!Most of the faults with a multimeter + screwdriver can be solved, the novice into a god on the four words -trial and error. On the assembly line, dare to tear down and repair is the way to go!
(Editor drifting away with a screwdriver in his mouth)
