Bit rot in micro controllers? (2023 Update)

Ladder Logic was invented so factory-floor guys, who used real relays to interlock and control things, could program PLCs to replace the relays when they died. It's pretty simple and makes sense for that case.

Sounds like a sensible way to fix a pellet stove without making it into a giant project that has to be done in freezing weather.

Reply to
jlarkin
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Time-delay relays are included, but old wired systems had pneumatic or electronic td relays too. But LL can get hairy if pushed too far, with analog functions and PID controllers and such. But fine for bang-banging some solenoids and motors and such. The industrial-level i/o of a PLC is nice.

Reply to
jlarkin

I had a dishwasher that wasn't drying the dishes, so I started replacing parts, the heating element (didn't actually replace it because the one in the dishwasher checked good), the thermostat, and the control board itself. It worked for a while after replacing the control board, but, then, started acting up again. I finally found a maintenance manual the showed me how to reset the controller by pushing front panel buttons in a particular sequence. This fixed the problem - for a while. Periodically I have to reset the controller to get it to dry the dishes again. Somewhere in the software it detects a fault in the heater circuit and stops energizing it out of an abundance of caution - but doesn't display an error code.

Just the other day our washing machine began acting up (filling with water during a spin-only cycle). I got on the phone with LG tech support and found out how to reset it. This involved unplugging the machine and holding the Power button down, then plugging it back in. This fixed the problem.

I will probably do a Youtube video on this because it could save people an expensive service call.

Reply to
Flyguy

Yes, I even took a test about that (to become a US citizen). It works a bit differently here than in Norway. From your reply-to domain I assume that is where you live.

Different here. In contrast to many other countries the US has ballot measures, weher voters actually do decideon individual issues.

Again, different in the US. You can actually vote for, say, a Republican president but then for a Democrat representative. You can even vote in (or out) the local sheriff here. Same for the attorney general. The party does not decide who that will be, the voters do. I assume you aren't an American and then this might sound unusual but that's the way it is.

Reply to
Joerg

I once recommended that a controller based on pneumatic logic (2000psi, IIRC) should not be replaced with microcontrollers.

Introducing electricity to unmanned offshore oil/gas platforms raises a whole lot of new failure modes :)

Reply to
Tom Gardner

... especially when rugged interfaces are beneficial.

Reply to
Tom Gardner

I designed the throttle and engine room controls for the navy's LHA ships. They couldn't find people to maintain them so they ripped it all out and went to pneumatics.

Reply to
jlarkin

2000psi ??

where they looking for 5000V microcontrollers too?

Reply to
Lasse Langwadt Christensen

Nothing wrong with a bit of noise immunity :)

My very limited experience was, gulp, 40 years ago. However,

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phrases like "The HLE10-CPC is a high-pressure logic element (350 bar / 5075 psi), normally-closed, pilot-to-close, and features a rated flow of 80 lpm (21.1 gpm)."

So my memory is in the right ballpark

Reply to
Tom Gardner

that's hydraulics not pneumatics ;)

Reply to
Lasse Langwadt Christensen

The ones I was concerned with were gas-based. Gas is a fluid.

Hydraulics or pneumatics is a sufficient description for me :)

Reply to
Tom Gardner

I had to make a custom automated machine controller that was easily programmable some years ago, so I created a textual LL and associated command-line LL compiler using Unix tools like GNU Bison and Flex.

Compiled virtually instantly on any PC and spit out a token file that was interpreted from EEPROM by a program running on an MCU.

I think I'd do it differently today, but there was also an issue of securing the 'crown jewels' part of the code (which lived in the MCU).

Reply to
Spehro Pefhany

Probably as good a way as any.

It is a simplified version of Nassi-Sneiderman diagrams which can in principle at least be used for general programming. I was briefly a fan of them once upon a time thinking that they might make programming logic communicable to the suits who make the really important decisions.

Detractors called them nasty spiderman diagrams.

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I moved on before it was ever given a chance to really work. There was a lot of "don't bother me with the details - JFDI" from my superiors.

Doesn't he just need a massive high power on-off switch if that is the only function that has really failed?

Probably not a good idea to start a war with the thing in mid-winter.

Reply to
Martin Brown

Yes, I live in Norway.

That's a different matter. I think it is a good thing that you have these single-issue questions that are sometimes asked alongside a normal electoral vote. Most Western democracies only have such direct questions very occasionally - such as the UK's "Brexit" vote. (Switzerland is the odd one out, having more referendums than most countries, and thus being a bit closer to being a direct democracy.) However, such direct questions are only relevant for the issue being asked - how people answer to "should this state legalise marijuana?" is completely irrelevant to how the utility companies work in the state. So unless you have a system where the general public can somehow decide which issues get these extra ballot questions, you are in the same state.

I am not an American, but I /do/ understand how that works. And it really isn't that different from other representative democracies except in the details. (In particular, non-political positions in most countries are appointed based on normal job qualifications. This means a sheriff or attorney general is, at least in theory, given the job based on qualifications and expected ability at the job, rather than their ability to canvas votes, popularity with the public, or their personal politics.)

We have political governance at three levels here in Norway - local county, regional, and national. (Obviously we're a much smaller country than the USA, and we are a single nation rather than a federation of states, which limits comparisons. It might be better to think of comparing a US state to the country of Norway. And as a kingdom, we don't have any equivalent to a president or a governor.) We can - and do - vote for different parties at the different levels. We can - and do - vote based on particular candidates as an alternative to simply voting for a party. And we have lots of parties to choose from, rather than the American three of right-wing, even further right-wing, and irrelevant (a.k.a. "independent"). Just like you, especially at the more local level it is quite normal for people to vote against their usual party preferences simply because they believe a particular person is better suited to the job despite their party. (In fact, we even have a somewhat odd and complicated system in the ballots where, in addition to voting for a particular party, you can give "likes" or "dislikes" to individuals from the same or another party, which influence that person's position in their party lineup.)

Reply to
David Brown

one might be surprised to learn that many steel, aluminum, and refinery plants are controlled by PLCs (level 0/1) controllers. These are large scale applications. They do much more than simple relay bang bang control. A number of universities have incorporated teaching about ladder logic and PLCs into their curriculum - they see it as a way to enhance the attractiveness of their student products to industry. J

Reply to
Three Jeeps

PLCs have progressed far beyond ladder logic. They are in actuality complete computers programmable in a variety of languages. My brother took over a design from Ft Detrick that uses a PLC to monitor fish which are excellent sensors for water pollution. When irritated by pollution they cough which the PLC detects. I'm told the program is a bit of "AI", whatever that means. At least they didn't call it fuzzy logic. I assume it is in actuality a bit of signal analysis software. I dunno, maybe it was faster/easier to train an AI with many examples of fish coughs rather than to try to figure out what filter parameters to program. It's just a mention of AI recalls the example where the military trained an AI to distinguish Soviet vs. friendly tanks. It did perfectly in training but crapped out in the field extraordinarily. Seems all the photos of friendly tanks were daytime photos and the Soviet tanks were all night photos. What do you think the AI was picking up on?

Reply to
Rick C

Your imagination is fairly accurate!

Ladder was originally designed to let automation engineers emulate the kind of control systems they had used before - relays, timers, counters, and occasional complex parts such as PID regulators. Basically, it just like drawing programmable logic using a schematic editor, except that you usually have a vertical structure (like a ladder). As PLC's have become more sophisticated, they have gained more and more "black box" components that are very remote from the original idea, such as boxes for handling web protocols or SQL database queries. And as sizes have increased, so has the unwieldiness of some tools - for some PLC's, the tools don't even have good ways to allocate or track relay numbers. (Imagine assembly programming without any directives for allocating space, and perhaps not even macro names - all your variables and addresses are entered manually by number, tracked and documented in a spreadsheet separately from the program.)

Other tools are more sophisticated, and some provide alternative text-based entry with written logical expressions rather than webs of relay symbols.

Reply to
David Brown

We visited a classroom at Sierra College, the branch in Truckee. There is a 2-year course in factory automation that has a 100% rate of job offers to graduates. The prof used to post here.

Going to school for two years in Truckee, on the stunning campus, learning real stuff with no student debt, major expense lift tickets, and then running the enormous Budweiser factory near Sacramento, doesn't sound like a bad life. One of his female grads did that.

Reply to
jlarkin

Yeah, running a beer factory is the High Life!

Reply to
Rick C

We usually have half a dozen or more on each major ballot. I strongly believe this is good.

They do decide that, by gathering the required number of signatures beforehand.

It is a BIG difference. We elect sheriffs and attorneys general. That's how it should be.

We can do that as well in the US.

Sorry, but that is leftist drivel, largely propagated in your media.

Interesting. They do not let us "unfriend" any others up or down the ballot but I also think that's not necessary.

Reply to
Joerg

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