PLCs are basically industrial-grade computers that can be programmed to do tasks, sorta like
microcontrollers but most PLCs have built-in encoders for motor control, support for modbus, and more…
Basically, if you are not familiar with BASIC, C, Java, or assembly language, PLC Ladder Logic language
might be the way to go as it has been proven in the industrial field for factory automation and more.
Ladder Logic is a way of programming without using any code. Personally, I do like to use Ladder Logic at times
because it’s a different way of looking at the embedded world.
Here’s a good site about PLCs (Programmable Logic Controller).
A nice detailed overview of PLCs from what is a PLC to basic instructions of a PLC.
Wikipedia has a good article on general history of PLCs.