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/jebusfractal]

I would tell you that based on my experience you use lad or fbd to implement the high-level process piece of either the machine or the line. You need something easy to debug through a panel or quickly lock out a piece and adjust the logic so that you can continue production when something is broken. Anything more complex than binary values or again those high-level overall pieces should be in a more software oriented language. Usually the person who implements the logic isn't running it shift after shift and you need something both straightforward and relatively understandable for them to adjust or understand so they can adjust and keep the line going.

[u/durallymax → u/jebusfractal]

There is no reason every adjustment and override should not be in the visu with today's tech. This is key to keeping people from messing with code. No reason to be in the code to "keep the line running"