This Pre-standard IEC 61804-2 is applicable to Function Blocks (FB) for process control and specifies the Electronic Device Description Language (EDDL). This Pre-standard IEC 61804-2 specifies FB by using the result of a harmonization work as regards several elements. a) The device model which defines the components of an IEC 61804-2 conformant device; b) 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; c) The Electronic Device Description (EDD) technology, which enables the integration of real product details using the tools of the engineering life cycle. This pre-standard 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. NOTE A real system fulfill all requirements of part 1, add the missing elements in this pre-standard in a technology dependent way. The conformance statement in Annex B, which covers the conformance declaration, is related to this pre-standard only. Requirements of part 1 are not part of these conformance declarations. The harmonization work for FB was carried out at an abstract level that allowed the definition of the common features in an unique way, offered by the several technologies as well as some complementary features that answer to the user requirements and that are expected to be implemented in the future. This abstract vision is here called the conceptual FB specification and mapped to specific communication systems and their accompanying definitions by the industrial groups. This specification is also based on the abstract definitions of IEC 61499-1. NOTE This pre-standard can be mapped to ISO 15745-1. The EDDL is ready for use and fills the gap between the conceptual FB specification and a product implementation. It allows the manufacturers to use the same description method for devices based on different technologies and platforms. Figure 1 shows these aspects. There are solutions on the market today, which fulfill the requirements of this pre-standard and show how the conceptual specification is implemented in a given technology. New technologies will need to find equivalent solutions (see Figure 4).

IEC 61804-2 Ed. 1.0

IEC 61804-2 Ed. 2.0