An overview about IEC 61499 and nxtONE
The IEC 61499 standard, since 2005 a public standard is a specification for modelling distributed automation systems on the basic concept of function blocks. The standard addresses the topics of distribution, parallel processing and modularity in industrial automation systems.
The standard describes the topics of:
Interoperability, the communication and interaction between devices
Configurability, the configuration of devices with software, even if the software is from different manufacturers
Portability, the usage of libraries from different manufacturers and applications from foreign software tools
The architecture part of the standard describes the
- Function Block Model
- Execution Model
- Distribution and System Model
- Device Model
- Resource Model
- Device Management Model
The function block is the most common used part of the standard for an programmer or system integrator. A function block consists of an Interface for Event and Data inputs and outputs. To take care for data consistency the events are associated to data signals. This is called the WITH Construct of the Function Block.
A Basic Function Block has on or more Algorithms and an ECC (Execution Control Chart which defines the state machine and algorithm calling sequence within the function block.
A Composite Function Block combine several Basic or Composite function blocks by a function block network to a new function Block .
A Service Function Block is defined within the runtime (firmware) and interacts with the resource layer. This will allows to access to the hardware signals or communication functions of the unterlaying hardware.
The function blocks within a function block network are graphically connected through lines for events and data. These lines define the data and event flow between function blocks in the automation program.
Everything is stored in XML files. The XML schema is part of the standard.
nxtControl is a specialist for IEC 6199 runtime systems and more (see also nxtControl nxtONE). They have ported their runtime system for different hardware platforms, operating systems and chip architectures. This includes also the LEGO MINDSTORMS EV3 for training and demonstration.
The IEC 61499 standard is used in the complete industrial automation layer on the device level. Function blocks are used for the automation program, for accessing the hardware IO signals, for the device to device communication, for interfacing and communication with HMI and SCADA systems and for integration and communication with foreign systems, such as databases, MES systems and so on.
(Images and parts of the text with friendly permission by nxtControl)