IEC 61804-2:2006 Specifies FB (Function Bloks) by using the result of harmonization work as regards several elements:
- the device model which defines the components of an IEC 61804-2 conformant device;
- conceptual specifications of FBs for measurement, actuation and processing. This includes general rules for the essential features to support control, whilst avoiding details which stop innovation as well as specialization for different industrial sectors. It defines a subset of the requirements of IEC 61804-1 (hereafter referred to as Part 1) only, while Part 1 describes requirements for a distributed system.