Well, I recently finished an undergrad EE, and am working in control systems for my masters.
A couple of course in classic control systems (with some on discrete / digital control), coupled with some hands on labs should be plenty to know for basic industry. The rest can be picked up (like ladder logic and PLC's, whatever the industry uses.)
If you want to be developing advanced control systems, I suggest reviewing robust control, adaptive control, and estimation methods (observer and parameter estimation techniques) as well as some understanding of non-linear systems or at least how to address their effects in linear analysis. That should give you a good idea about what modern controls can do.