I'm trained as an instrumentation and control engineer, but I really love IT and want to increase my knowledge for that field. What can I do to make a career change to this field?

First thing first, learn more. But since you do not have the luxury of spending four years getting a degree in an IT branch, learn only what will help you. IT is a very vast field. Which part of IT are you interested in? If you are interested in application development (coding new applications that will be used directly by non-programmers), I suggest you learn Java/Python. Python is easier for beginners, but I retain a soft corner for Java. Take your pick.      Do not be bogged down by the details of the language syntax. What matters is learning to think in terms of code. Not learning to write in a particular language. Once you know how to think, you can pick up any language you need in a month at most.      Ok, so once you have learnt one language well, start building things. Don't think in terms of what will sell. Think in terms of what you want. May be you have always hated a particular piece of software? Build your own. If a non IT degree holder wants a good IT job, he needs to show that he knows the work. Start small, and keep building things. If you have working pieces of code - good code, most IT companies will not give a damn that you don't have a CS Degree. If you are interested in mobile application development, learn Android. Not because it is better than other mobile OS, but because it has better resources available on the web. Start building apps. Start small and grow. Even if you are not interested in mobile app development exclusively, learning Android and building apps will be good for your resume. And more importantly, it will teach you something Python/Java can't. Event driven programming. Go to hackathons, any development contests you can find. And don't just build apps there, build contacts. Get to know people who are working in the industry. Since you do not have a degree, it would help greatly if the recruiter knows someone who can vouch that you are good. If you are interested in systems engineering (building stuff that will be used by other programmers), then getting a career is more difficult. You can learn about operating systems, and try building one of your own. Or try customizing Android to create your favorite OS. You will have to be more patient. Understand that this is a field that needs more theoretical knowledge than application development. May be you can try getting a degree through a correspondence course. If you are interested in networks, again getting a job is probably more difficult. But you can go for certification programs. As far as I know, they do not have degrees as pre-requisites. You will have to work triple hard, but if you are interested, you will be successful :-) If web development is what you are interested in, go out there and start building websites. There are many 'work-from-home' opportunities in web development. They pay pretty less, but the experience will certainly help you go further.