or failures. “Virtually all process automation is coming down to accurately controlling a valve. If the automation doesn’t control the valve well, the process is shut down,” says Charlie Piper, Foxboro Automation fieldbus product manager at Invensys Foxboro, a process controls vendor in Foxboro, Mass. “The asset manager will tell you if the device is slow to respond and let you know if the device has a history of problems.”

Managing acronyms

The fieldbus network carries the data from the device to the user interfaces. The main fieldbus protocols include Foundation Fieldbus, Hart and Profibus. The three main standards organizations have worked together on their protocols so device data can be read by any control system, allowing plants to use devices from different vendors.

There are a number of acronyms associated with fieldbus technology. DD is the device description. This tells the network what type of device is connected. DDL is the device description language that communicates the “smart” information coming from the device. If the device is failing, it communicates this information in DDL.

A couple of years ago, the Fieldbus Foundation, Hart Communication Foundation and Profibus International collaborated to come up with EDDL, the enhanced version of DDL. EDDL was created for advanced visualization of intelligent device information to maintain the integrity of DD across all three communication technologies.

EDDL was also designed to include improved user interface with the support of menus, windows, tabs and groups with the added user tools of graphs, trends, charts and dial indicators. Instrumentation and control system vendors participated in the validation of EDDL, with the goal of making the language vendor-independent. The idea is to allow users to choose best-in-class instruments that can be used on the network no matter what control system the plant is using.

The asset management system takes the information coming from the devices through the fieldbus network and makes sense of it in the context of the individual plant. Sometimes called plant asset management (PAM) systems, these tools organize the network information according to the user’s needs. “Asset management systems allow a change in philosophy. You have better information about the device, so you know what will happen if you don’t change the device next week,” says Ron Helson, executive director, Hart Communication Foundation, in Austin, Texas. “It allows you to take advantage of that information and take action before a failure disrupts your plant.”

For maintenance, PAM systems answer questions such as, “What equipment may fail if it doesn’t receive maintenance?” The maintenance view will also show wear or faulty behavior of individual devices. For operations, PAM answers questions such as, “To what extend can I increase output without risking quality or safety problems?” The operations view also includes information on adjustments that can be made to prolong the life of the assets.

A PAM system can also include an asset information register, which shows how the asset fits in with the entire plant system, and a data harvester, which can access historic information on the behavior of individual devices. The data harvester can also monitor asset behavior such as vibration, displacement and electrical functions.

The data from the harvester can move through the condition monitor, which holds the baseline condition. If the data doesn’t match the model, the operator can be alerted. Finally, a PAM system can include an asset health analyzer that acts on exceptions found in the condition monitor, and classify the exception by type and need, such as potential problems with lubrication, vibration or process discrepancies.

Asset management systems offer plant operators a new look at their process operations. As well as using the data for maintenance, operators are also starting to use device data as a tool for optimizing plant equipment and operations. Because the asset manager can track plant data and store history, operators can use the data as a match against an idea model of plant operations. Through tweaking the devices, operators can squeeze more throughout out of the equipment, while closely moni-toring the potential for stress and thus avoiding device failure.

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