Most of the available training for this stuff is vendor-specific, vendor-provided and really expensive to undertake. Indeed, many vendors have solution provider

Most of the available training for this stuff is vendor-specific, vendor-provided and really expensive to undertake. Indeed, many vendors have solution provider networks who will prefer to do this programming for you, because it is so unintuitive/dangerous/error-prone. You can, however, learn the control systems by grabbing and reading the manuals. Look for manufacturers then seek out manuals. Many are online though they are often not the latest edition as some manufacturers now seek to keep this internal to paying customers. All the systems I have seen use G-Code variants with manufacturer specific extensions. Many now offer GUIs to help with spatial planning, multi-machine integration, common code generation, etc. However, at the end of the day it is still nearly all about generating/writing/modifying/replaying stored G-Code.