Siemens Simatic
Siemens is very large with a very large scope of operation, as such they have good market reach. This means good documentation and usage in the field so if you have a problem it typically isn't too hard to find the solution. That being said they make it very hard to even get a look at their tech if you are looking to expand your knowledge or do some basic research. Try downloading a trial version of their development software and you'll know what I mean. Here are their current main offerings for PLCs: Simatic S7-1200 - Compact/Small "Basic controllers are the intelligent choice for compact automation solutions with integrated communication and technology functions. They are available in standard and failsafe versions." Simatic S7-1500 - Advanced "You’ll achieve the highest productivity and product quality in your production process by using SIMATIC S7-1500 with its fast backplane bus, PROFINET performance, shortest reaction times, and a command processi...