2 weeks back we had plc comms issue, it lost communication for approximately 10-12 seconds and came back. This plc runs a feed auger and before the plc lost communication the feed auger was running in forward direction after the plc lost comms and came back, suddenly the feed auger started running in reverse direction on its own then it would not shut off to put it back into forward direction.
I tried doing some research but didn't find any proper resource. Can someone help me figuring out what exactly would have happened?

 

How does the PLC control the auger direction and start/stop? By comms or wired I/O? If I/O is it connected to the PLC or via comms?

 

Would help to know the brand and model of PLC, and if it is networked too. Is there a switch involved, possibly a managed one? That way you can do some checking of logs etc. In addition to above comments.

 

The current generation electronics are very sophisticated, and they use multiple latest technologies to work together. One such thing is very thin silicon wafer (4 nano meter is currently in use) so that the manufacturer can cram more and more transistors & it provides higher power efficiency. But the downside of it is, it become super sensitive to muon particle created from outer cosmic space. Its humanly impossible to shield them since it can penetrate even an 8-meter-thick lead wall. The only mitigation is to have higher redundancy of your control electronics as applied in Safety systems, Satellites etc., This issue is very common to FPGAs, even Memory elements as well. ECC Memory is still not that common in cheaper PLCs. Do note that it’s a bit flip in your case has caused the direction changes. This is experienced in many of the Electric Vehicles while running suddenly it will go in reverse direction at the same speed. There are many reported incidences around the world where EV 2 wheelers the driver is tossed in air and the vehicle gone in reverse direction at full speed.

 

Some manufacturers do have watchdogs implemented to detect such memory corruption based on check sum & trigger a reboot of the CPU – which is their designed recovery mechanism. At that time, you will lose communication with the PLC.

 

Hmmmmm...

 

Yeah, the cosmic ray thing. It's that fall back position for "who knows why it failed?". Blame it on cosmic rays.

It wouldn't be a programming bug that never accounted for a cold start in the absence of a valid persistent direction variable, which maybe was battery-backed with a dead battery?

 

Yeah, the cosmic ray thing. It's that fall back position for "who knows why it failed?". Blame it on cosmic rays.

It wouldn't be a programming bug that never accounted for a cold start in the absence of a valid persistent direction variable, which maybe was battery-backed with a dead battery?

Its proven there are algorithms to detect them. There are several white papers from every chip manufacturer (Intel, Altera, Xilinx, toshiba, hitachi, even PLCs and DCS vendors)
I have been researching on this issue for last 2 decades, I have detailed report from French space agency (which can't be shared here due to Intellectual property)

Sharing few links


A detailed explanation is available in this YouTube Link:

Cosmic Ray Muon Detector (CRMD)
https://web.iucaa.in/~rpl/Experiment4.html

Cosmic ray muon causes glitch in electronic devices
https://resou.osaka-u.ac.jp/en/research/2018/20180529_1

Understanding Muon's path & directional changes by Royal Institution of Great Britain:

https://www.facebook.com/video.php?v=809354174235679

The unseen impact of cosmic rays on electronics
https://www.electronicspecifier.com/news/blog/the-unseen-impact-of-cosmic-rays-on-electronics

MITs handheld muon detector
https://news.mit.edu/2017/handheld-muon-detector-1121

Cosmic muons
http://www.cosmicwatch.lns.mit.edu/about

Identifies and measures the momenta of muons
https://atlas.cern/Discover/Detecto...ion detectors of the,electrons out of the gas.

DETECTING MUONS
https://cms.cern/detector/detecting-muons

 

We can all accept this is possible, but extremely rare or it would cause a lot more issues. So why go for the rarest, most unlikely event to troubleshoot a problem? Occam's Razor, the most likely problem is the most likely reason.