Working in lab also need some statistics knowledge. I knew someone whose major is hygiene use SAS well(It's several years before in China). The salary of SAS expert is more than double as your current salary.But you have to work from the entry level and employer always like to hire experienced person. You'd better have chance to use SAS in your work(like some lab data statistics) and gain some experience while learning.
For PLC knowledge, there're manuals in some companies' website, like www.ab.com, but you can't learn it without software and device. And experience in this fields are more important for employer's consideration and is also more difficult to gain the experience than the computer language.