Well this was a fail.
I burned out five of the eight white LEDs when I swapped in the voltage regulator so they’re all in the scrap pile (I’m collecting these now, maybe I can use dead LEDs as light diffusers or something). I tried using some yellow LEDs with resistors this time, and it just went haywire again. More additions to the scrap pile.
I just got a big hint on what the problem is with this method. When I tried powering it up with all of the lights on, everything turned on for a second then shut off completely (the hardwired power indicator and emergency stop button came in handy here). I think it has to do with power budgeting from the 24v supply. I’m already pretty sure the control circuits and the supply to the actual PLC modules are supposed to be separate. I think if I had a separate power source for these LEDs, I wouldn’t be having so many problems.
So now what?
Well, I’ve come to the decision not to go any further with my PLC trainer project. In fact, it’s being downgraded. It’ll pretty much revert to the first generation, more or less what you see in the PLC 101 post but with neater wiring. No more side panel LEDs. No more relay. No more additional output module.
The point of the PLC trainer was to have something physical I can play with to practice my programming on. When I accidentally ended up with extra parts, I wanted to run with it and pile on more into the trainer. It’s had problems and the bandaids were adding up. I’ve promised myself I will not pour any more money into this project. If I were to estimate, everything that has been purchased for the project is around $400. That’s way too much and I’ve been so distracted by upgrading the hardware that I’ve barely practiced programming on it. I don’t want to say I regret building this thing, but I wish I was more rational with my decisions for it.
Some day, I’d like to use it in a practical project or downsize even further, using small lights and toggle switches and buttons. Or sell the parts off. Whatever happens first.
So the PLC trainer isn’t exactly dead. I will be posting my practice programs whenever I get around to making a new one. The last one I worked on, but did not complete, was a mixing tank process but it relied on the side panel LEDs so…
Stay tuned for more. Thanks for reading!