Secure communication in PLCs is rapidly gaining importance and in some projects the deployment of PLCs with TLS (Transport Layer Security) security is already a requirement. In the following, we will learn the basics of encryption and authentication and show some scenarios from a design and application programming perspective. More information on the whole issue, detailed descriptions of connection establishment and the like can be found on the Internet, we will only discuss the basic principles and especially the implications for the project organization and the setup of PLCs and other programs. Sometimes we come across the abbreviation SSL (Secure Socket Layer), TLS is its more modern successor.
