In contrast to the systems for supervising and control the processes in the Energetics, Metro, Railway etc. which are typical Remote Control Systems, by which the process data transfer is performed over public or corporate communication networks, the Industry аutomation systems are typical process control systems.
Here the communication infrastructure is granted and no public networks are used (as in telemechanical systems). The objects are located in a small area with easy access, thus the communication infrastructure is build as part of the system and adjusted to fit its particular requirements. This greatly decreases the complexity of the communication problems.
An automated object is any technological robotic section, production line or factory hall including:
- various robots
- Computerized Numerical Control – CNC machines
- transport devices
- machines with specific purpose
- intelligent control- and measuring devices – Intelligent Electronic Devices – IED etc.
Some of the technological devices, like robots, CNC machines etc. have their own controllers. The information flow among those devices is done by “process networks” or Field Bus networks like Profibus, DeviceNet, CAN Bus etc.
The interface with the others devices go directly over digital I/O’s. They are managed directly by the system.
The technological devices within a system are interrelated and therefore a single unit could not be managed entirely from inside.
The coordination and synchronization between devices implies that there exists a data acquisition center to collect, process and analyze the information from all units and then create subsequent commands and actions. Thus if an action requires information from more than one device, it is completed by the head of the system.
Otherwise, the system is created as much decentralized as possible by exporting functions and responsibilities on lower level devices.
The criteria to define the functionality of process function and there location inside the system hierarchy are:
- the function has to be maximal independent
- the data exchange has to be minimal
- the necessary information has to be available on this location
The system uses hierarchical structure and consist of:
See here Hierarchical structure of the system
Controllers of robots, machines, measuring devices and Field Buses are located on the process level. Furthermore the information exchange between RTU’s Station Computer and technological devices is also part of it.
The Station Computer collects, analyze and process information by technological devices in a technological section, production line, factory hall etc. After the synchronization and coordination has finished, subsequent control commands and actions are executed.
Station Computers with Front_End Servers are located on the object level. This level is responsible for information transfer between RTUs to upper level devices by means of IEC 60870–5–101/104 protocols.
Data delivered to Front_End Servers is transferred to SCADA Servers, where technological system functions are executed, including interaction among devices. The SCADA Servers transfer information to local Operator Working Stations – OWS to create visual representation of the production process.
A technological section, a production line or a factory hall define different scales inside an automation configuration and the system supports each scale with its devices in parallel and independently.
For this purpose the Station Computers work as servers to supply more than one client with the data required.