TABLE OF CONTENTS This chapter reviews a special form of function block that provides interfaces into the underlying resource and communications systems.
Specifically we will:
discuss why Service Interface function blocks are required and show where they can be used
review standard input and output data and event variables required in Service Interface function block type definitions
review the special notation used to describe the sequencing of external interactions with Service Interface function blocks
consider some examples of Service Interface function blocks and look at where they could be applied
finally we will review Management function blocks, which are a further specialised form of Service Interface block for controlling the creation and management of function blocks within resources and devices.
So far we have focussed on function blocks used to model the internal behaviour of a resource. At the end of chapter 3, we reviewed the creation of a simple distributed application and showed that this was only possible if additional Service Interface (SI) function blocks were provided to communicate data values and events between resources. In fact, wherever any form of interaction is required between function blocks within the resource and the external world, there is a requirement for an SI function block. IEC 61499 does not set standards for particular types of SI function blocks but does stipulate that these forms of function block should be defined using a standard set of input and output variables and input and output events. There is also a special notation used to...
