Here's how Shell upgraded from a pneumatic instrumented plant to a fully digital control system.
Decades of operation, modernization and expansion have left many chemical plants with a somewhat haphazard automation mix of different controls, process control systems, remote I/Os and field devices. The various components may use different communication protocols such as HART, PROFIBUS or FOUNDATION Fieldbus, and are often based on different device integration technologies.
The changes in social environment, such as globalization of enterprise activities, depletion of natural resources, and eco-oriented movement will affect the structure of mass production. Control systems must be prepared with flexibility and scalability in both size and function to adjust to the changes.
To configure a compact, low-power medium attachment unit for field buses, i.e., a fieldbus MAU, an IC comprising a power generator, transmitter/receiver and other functions is needed. While we at Yokogawa had already developed a fieldbus MAU IC, we have now developed another MAU IC that includes large-scale design changes made mainly to comply with the low-power signaling requirements of the fieldbus specifications.
Progress in digital signal processing and network technologies has enabled advanced functions which cannot be achieved by traditional field devices with 4-20 mA signal, to be implemented on field devices. Standardization of international fieldbus specifications, notably the FOUNDATION™ Fieldbus, has enabled users to build optimum field networks comprised of freely chosen field devices from various device vendors.