This pocketbook investigates the suitability of a Raspberry Pi 3 Model B for industrial applications with real-time requirements as a cheap and convenient alternative to a Programmable Logical Controller (PLC). Terms such as real-time, scheduler policies and multi-threading will be mentioned in this book. It will discuss the effort that is required to make a Raspberry Pi ready for industrial applications and the proper programming language. Different tests with three Raspberry Pi's have been performed to show the real time behavior of a rt-preempt patched kernel. One running with the standard Operating System (OS) Debian 'Jessie' and the others with the same real-time configuration (Debian 'Jessie' with rt-preempt patch). The time deviation with regards to 100 % CPU load, less than 20 % CPU load, different available rt-schedulers and in respect to the real-time communication behavior in the network has been analyzed.