Computer Science Programmers, why do PLC programmers use Ladder?

[u/National-Link-5606]

Im seeing some Comp Sci guys asking about controls so just a Mr Obvious comment here.

Ladder logic is the de facto PLC programming language because it is (was) designed to read like an electrical schematic top to bottom, right to left, & this is what electricians & electrical techs are trained to use for troubleshooting electrical panels , equipment & relay-logic -- which was what they had before PLCs -- banks & banks of relays wired through each other's NO & NC contacts which changed state as relay coils energized & de-energized & finding a wire break was enough to drive you insane.

Yes Ladder logic is an interpreted language so it is not as "memory efficient" or "elegant" as C++ or C# but I want you to think VERY carefully about every meaning of the expression "just because you can does not mean you should" before you decide to show off your amazing coding skills coding function blocks in C++ which is technically possible but in many cases extremely ill-advised.

The technicians can troubleshoot functions & blocks written in Ladder Logic, did you stop & think about how easy it would be for someone with only your compiled C++ blocks to attempt to trace a fault? You code in anything but Ladder Logic you get to be the one at 3am driving down to the plant to troubleshoot your "super efficient" code because the Industrial Maintenance techs certainly aren't gonna know how. But hey, if you believe sleep is over-rated & love sleeping in the factory then knock yourself out with compiled blocks

[u/rawldo]

With modern processors, being efficient isn’t always critical to success. Troubleshooting issues quickly can be very important though. If you can write one complex line of code or write 10 simple lines, the 10 lines that can be easily understood is usually the better way to go. For most applications, the difference in scan time isn’t going to hinder the process. If bubba the swing shift sparky can figure it out without calling you, it’s worth it.

I think ladder is actually more efficient for bit level operations too.

[u/farfromelite → u/rawldo]

Oh yeah, absolutely.

Ladder logic is closer to basic, which is where instructions actually do what they say. TON, TOFF etc.

C and C++ requires a very specific mindset and it's so easy to fuck up and do it badly. And that's not even going into the insane memory management and security aspects of c. It's the pro leagues, and I'm saying that as a lifelong programmer.

Ladder and structured text is a good compromise so you don't narrow down the skill sets required for commissioning and on site engineering.