2018DIN EN IEC 61804-2:2018 Function blocks (FB) for process control and electronic device description language (EDDL) - Part 2: Specification of FB concept (IEC 61804-2:2018); German version EN IEC 61804-2:2018
2007DIN EN 61804-2:2007 Function blocks (FB) for process control - Part 2: Specification of FB concept (IEC 61804-2:2006); German version EN 61804-2:2007, text in English