Motorized Valves Control System Centralization: How Does it Impact on Reliability, Costs and Performance?

The master-slave topology, based on programmable logic controllers and their respective controlled equipment are often characterized by the use of intermediate devices called Master Stations that perform the interface between data processing and triggering unit, and are responsible for protocol conversion, data acquisition, priority setting, and management of slave devices. For the most part, these intermediate control devices are systems developed by manufacturers and process equipment suppliers themselves, more specifically in the control of large quantities of motorized valves in industrial plants. As a result, a project was implemented to implement control and supervision information exchange routines of the motorized valve system directly through the PLC / Supervisory System, eliminating the need for the use of intermediate control devices. The results show high simplification in the architecture by removing the Master Station and changing the network topology, attaining an overall cost reduction, and a great improvement on performance, by the higher communication speed levels, especially for decreasing the latency delays; lastly, control centralization into more robust equipment and network segregation of the valve system, turned it easier to diagnose failures, ensured operational continuity, reduced the statistic of failures and increased the reliability of the process.