ABSTRACT
With the development of control theory and technology, computer technology and
network communication technology, networked control system (NCS) came into being,
and has brought great changes to the field of industrial control. Networked control
system enables the distributed control nodes or devices in different geographical
locations organically as a whole, provideed the basic conditions to achieve the
integration of enterprise management and control, remote monitoring and control. It
also greatly simplified the control system design, improved system reliability and
control quality, is the inevitable future development of integrated automation technology.
Ethernet technology is a widly used network technology, especially in industrial
automation and control LAN. As the applications of Ethernet technology in the field of
industrial control, field bus technology and Ethernet technology combined with each
other, the networked control systems will have greater development.prospects in the
future.
In this paper, we combined the networked control systems relevanted theoretical and
practical engineering requirements, used Rockwell Automation NetLinx industrial
networking platform solution, designed and implemented Songjiang Wastewater
Treatment Plant Networked Control Systems, focused on the problems of realization of
the key technologies. The system embodies the control system networked, integrated,
intelligent trend, realized the control network system design and implementation in the
this trend, the integration of a variety of field buses and construction of real-time
database.
Firstly, by using industrial networking platform program NetLinx, constituted control
network of the optical fiber Ethernet and Fieldbus. Because the system is large in scale,
geographic dispersion, more monitoring points and complicated in control
characteristics, according to "distributed control, centralized management" design
principles, we designed and implemented a networked control system composed of
three layers: information layer, control layer and field control layer. As a variety of bus
co-existence in industrial control systems we use protocol conversion gateway,
Profibus-DP fieldbus will be integrated into the network system.
Secondly, by using ControlLogix controller, realized all sewage treatment process