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Industry: Waste Water
 Application: Distributed DAQ and Control

Distributed Data Acquisition and Control in Waste Water Treatment Plant
 Environmental protection is becoming more and more important as worldwide industry develops. In many manufacturing plants, environmental monitoring is essential. Recently, the ADAM-5510 was chosen for a distributed data acquisition and control system in a water treatment plant. The ADAM-5510's optimal performance/price ratio was, no doubt, a telling factor in winning the contract.

System Requirements
The subject wastewater treatment plant has four CAS (Carbon Absorption System) reaction pools, one wastewater pump room, one water-processing machine room and a central control room. Traditional relay controls did not meet system requirements, due to the harsh environment and complex industrial requirements of the wastewater treatment process. A PC-based distributed data acquisition and control system providing real-time monitoring was proposed. This system was chosen to help the plant's management supervise plant operations, and to achieve their optimal control goals. The plant's machine status, process status and control parameters will all be monitored.

System Architecture
The distributed data acquisition and control system will consist of a central controller, a mimic board, and six sets of intelligent field controllers. Each field controller will be connected to a local display, which will be able to be set locally. System communication will be based on an isolated, twisted-pair RS-485 network. Communication speed will be 9600 bps. The system architecture is shown under.

a) Central controller An Advantech IPC-610 with a PCA-6151 CPU card was chosen as the central controller of the system. The PCA-6151 features a watchdog timer which automatically resets the microprocessor after hardware or software failures. This feature reduces maintenance and increases system stability. Advantech's VisiDAQ 3.1 software was chosen as the system's human-machine interface. VisiDAQ 3.1 combines ease of use with the programming power of Visual Basic. It allows system designers to easily develop simple or complex data acquisition and control systems.

b) Intelligent field controllers ADAM-5510 systems were chosen as the field controllers. These are designed to independently perform a number of data acquisition and control functions. Their industrial toughness and immunity to electrical noise makes them an excellent choice. Each ADAM-5510 will contain an ADAM-5051 16-channel DI module, two ADAM-5060 6-channel relay output modules, and an ADAM-5017 8-channel analog input module. The control logic for each ADAM-5510 will be written in C language on a PC and will then be downloaded to the ROM-DOS in the ADAM-5510.

c) System communication In this application, each ADAM-5510 will be connected by its COM1 port through an RS-232 cable to a local 8031 single board computer with a screen. COM2 will be connected via the RS-485 network to the central controller and the mimic board.

Conclusion
The ADAM-based system will comprehensively perform data acquisition and control in the wastewater treatment plant, and centralize the information available to the plant's managers. The distributed design architecture will enhance system reliability and maintainability.

 

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