Plc Minutes: Fill & Download for Free

Maybe not my biggest, but certainly my most recent.So, the exterior lighting of my house is controlled by a programmable logic controller (PLC) where one of many inputs is a simple twilight switch (on when dark, off when daylight). My setup is a bit over-complicated for a small family home, but I enjoy playing with stuff like this. It's a geek thing.So, the missus asked me to modify the lights so they would turn on a bit earlier.“Just like, a few minutes before twilight. That’d be great, Love. You’re so smart with electronics and stuff.”I smiled confidently. I sure am, I thought to myself.Initial reasoning. I could adjust the sensitivity of the twilight switch, but that would require me to fetch a ladder, get some screwdrivers, open the switch and fool around with a resistor in a trial-and-error sorta way. No no, a simple software fix would be much easier and faster.Above: My twilight switch (source: Biltema).So…Turn on the lights. Ten minutes before it gets dark. Simple. Five minute fix I reckoned.I opened the PLC-software and got to work. In the back of my head, something didn't feel right, but I couldn't quite put my finger on it. I browsed the library for a timer function to add to my program. I quickly found it and started wondering how to integrate it into the existing program. It had to precede the twilight switch somehow. What to do, what to do.A few minutes into my fix it hit me.Turn on. Ten minutes before the twilight switch turns on.Ten minutes.Before the twilight switch.Turns on.Facepalm!I turned off my computer and fetched my ladder and screwdrivers.In case any of you failed to see my stupidity… The twilight switch is activated the second the light intensity falls below a certain level. It’s a simple sensor and on/off-switch. Unless my PLC is able to see into the future, how on Earth would it know when the on-signal from the twilight sensor is ten minutes away? Yeah, you can stop laughing now.So yes, I sure am smart with electronics and stuff.Edit: Thank you all for your input. A lot of creative suggestions. I’ve tried using astronomical data (sunset/sunrise) before but it didn’t really fit my needs. It doesn’t account for dark weather conditions (cloudy, rainy, foggy and so on). Only sunset/sunrise. Not actual conditions. As for delaying the lights 23h50m, that’s pretty clever, but not a fail safe solution :)Edit: Some of you suggest simply adjusting the sensitivity of the twilight switch. I know that is a solution (which I also point out in my story). My point is that I thought a software fix would be easier and faster.

For hours and minutes you can use 60s timers done bit as input of counter. Which shows output value as minute or hour.

College Class - Programmable Logic Controllers.It should be mentioned that I work with electronics for a living, and had for many years before taking this class. A lot of that involves troubleshooting.We were reading one chapter on PLCs and subsequent components, and the teacher posed a question in regards to “if this problem arises, what is the probably cause?” He meant in reference to the chapter we were on. It had something to do with timing sequences being out of whack at an automated assembly line.However, I looked at it for a minute, and did what I do at work:Break out the entire system (a little hard, since it was described over text), and began troubleshooting things down. I came up with like 10 possible faults, when the professor intended that we just find something that worked from the book.Obviously like four of my possible faults were unlikely for the symptoms seen. Wiring and the like.Of the remaining, I tried to determine which could actually cause the problems seen. It was supposed to be some card in the PLC cardcage, but I isolated it to a loose or dirty optical encoder - something mentioned in the next chapter.I included the answer he wanted, but I totally got a 100% on that assignment. :P