This book provides the basic knowledge concerning the use of Industrial Ethernet and communication buses in industrial automation. It starts with an introduction to fieldbus systems, to Ethernet and its specifications, and the structure and protocol architecture of TCP/IP. This is followed by sections on wireless networks, on protocols enhancing the availability of networks and a fundamental introduction to PROFINET. Practical examples show how to configure PROFINET IO networks, MRP rings, shared devices and I-devices with STEP 7 V5.6 and TIA Portal V15. The section on industrial security explains how attacks work, and illustrates measures, concepts and architectures that are used to enhance the security of networks. Examples of firewall configurations with TIA Portal V15 and SCALANCE S will help you to implement own projects. The next chapter presents a typical industrial network design and shows which components can be used for implementation. The book is rounded off by an outlook on digital connectivity and the Industrial Internet of Things (IIoT).