A prototype computerized control and supervision system (CCS) was designed and constructed. The user can, via a state of the art interface, control data acquisition, save and plot data, manage the system and respond to system alarms. Various sub-processes, including DO, are automatically controlled by the CCS. The CCS consist of a PC, equipped with AD/DA, and binary cards that communicates with the process via a switch cabinet. In total, the system uses 19 analog outputs, 18 analog inputs and about 50 binary signals. Pump motors are controlled by the CCS via frequency converters. DO is controlled by PID controllers that regulate airflow rates via valves. Binary signals are mainly used for alarm handling and presenting status of the equipment, i.e. pumps operating in manual or automatic mode. Linux, a public domain UNIX dialect, was used as the operating system and extended for real time processes. The CCS is implemented in C++ and the graphical user interface was created with Motif. Data values from the process is collected and stored as average values over ten minute periods.
The prototype computerized control and supervision system (CCS)
Carl-Fredrik at the plant. It does not smell bad here!
