November 15, 2007

Plantwide data networks leverage digital technology to the max

Timothy E. Hurst, PE, Hurst Technologies

It’s the network!

To get your mental arms around the concept of a PDN, stop thinking about traditional process control techniques and start thinking about how other industries, such as telecommunications, use networks. The Verizon television commercial with the geeky guy in big black glasses and his crowd of network specialists following the customer around is an apt visual.

A high-speed PDN can move critical information into and out of digital systems in near-real time and onto the screens of the operators and engineers able to maximize its utility. Though the capabilities of such networks were originally designed to meet the needs of telecommunication carriers, they have since expanded considerably. As the major computer networking companies like Cisco Systems and Hewlett-Packard have upgraded the speed and refined the practical implementation of such systems for industrial applications, suppliers of process control and plant distributed control systems to the power industry have been moving in the same direction.

The basic foundation of a PDN is physical: its fiberoptic backbone (commonly called a cable plant). Higher in the hierarchy are multiple layers of physical and logical networks. The physical networks embody actual cable and wire and intelligent network switches, while the functionality of the logical networks is defined by the programming of switches to effect specific types of data transfers at the right time.

In a telecom network, cell phone signals jump on and off the hard-wired landline network as necessary. Similarly, a PDN should provide connectivity for wired devices, wireless devices and communications, and enough bandwidth for expanded capabilities in the future.

Can you hear me now? A layered plantwide data network for wireless communications and sharing of equipment control and performance data. Source: Hurst Technologies