Part of defining a complete control system includes identifying how different users must interact with it. Interaction types to be considered range from data only to full graphical interface and from monitor only to full supervisory control. Other facets in this decision process are the type of system used and the method of providing information to that platform.

As system developers consider these issues, one factor increasingly occurring is management's desire to make production operation data available across a wider segment of the enterprise. Previously, the need or desire for real-time production status was limited to production supervision and process engineering. That has changed. In the new production paradigm, it is desirable for other groups, including management, to view this information.

However, providing data displays to multiple users is expensive if every station requires a software package license. With the growth of Intranet browser-equipped PCs in business applications, the use of HTML pages provides another option.

ErgoTech (Los Alamos, N.M.) has developed a collection of Java beans called Virtual Instrumentation Beans (VIB) that can be used with a Java editor to create applets for graphical data displays. These applets are simply launched from HTML files that can be accessed on the server machine by clients over intranet or Internet connections. This allows multiple users to view the production screens with a standard web browser; no special software is required on their PCs.

The VIB package includes a wide range of drawing elements plus several specific objects, such as pipe components and pumps. Additionally, ErgoTech includes a set of standard instrument elements, such as seven-segment displays, meters, and strip charts.

ErgoTech also developed beans that support control functions. These are typical control operators, for example, pushbuttons, sliders, and knobs that can be embedded and linked in the same way as the monitoring objects. VIB also includes active elements such as addition, scaling, clamping, and Boolean operators. These functions can be used to modify actions going to the control system or process data coming from the system.

When all of the JavaBeans included in the VIB package are used with a Java editor, the user can avoid dealing with the complexities of a full Java development system. In the VIB environment, users simply select a bean and place it on the editor page. From there the bean can be resized, its color scheme changed, and other physical properties modified. It can then be linked to data sources including data processing beans from the package.

VIB is a useful tool but care needs to be taken with system configuration in terms of software selection, especially the Java Editor. VIB is a helpful tool, but users must be careful during system configuration to select the right software, especially the Java editor. The user is advised to read the documentation from ErgoTech on the Virtual Instrumentation Beans package, Sun Microsystems on the Java Bean box, and from the vendors of the Java editor selected. This is strongly suggested because software incompatibilities exist between Sun Microsystems and Microsoft, particularly in Windows 98, that can affect the use of VIB.

This evaluation of VIB, release 3.02, was performed using ErgoTech's April 2000 release of Virtual Instrumentation Constructor (a no-cost development tool for evaluating simple screens), which runs under Microsoft Windows 95/98 or NT and uses Sun Microsystems Bean Box (jdk1.1.8).

For more information about Virtual Instrumentation Beans, visit www.controleng.com/freeinfo