far, PRASA has connected 212 sites to the SCADA monitoring system and expects to have all 1,500 sites connected by 2010. Matias is also developing the system further at the water plant in Maricao to do remote control. His goal is to tighten control with fewer people.

Strength through software

A strength of Wonderware’s platform is that it is component-object based. In other words, users can generate one template for monitoring and controlling a kind of asset, such as a pumping station, and use it wherever similar monitoring functions are needed. “If you want to change or add a parameter to a pump, you modify the template and deploy it to all of the running applications across the entire SCADA network simultaneously,” says Garbrecht.

Other flexible SCADA software exists, as PEMEX Exploration and Production (PEP) discovered when this agency of the Mexican government went looking for a way to tighten the coordination of its southern operations. It found LabView, a graphical programming language from National Instruments Corp. (NI), of Austin, Texas. This language not only comes with configuration-based SCADA tools, but also offers users the flexibility to develop links to PLCs and other industrial devices.

“A conventional SCADA package is configuration based, and a programming language is bolted onto it by way of scripts,” says Arun Veeramani, NI’s product manager for LabView. “If you have any customization, you invoke a script.” He claims that programmability of LabView removes the traditional boundaries between hardware such as programmable automation controllers and the SCADA application.

Removing these boundaries was important to PEP because the company had grown by acquisition and its various units contained a large number of disparate transmitters, PLCs, and other devices. Although the devices measured key data electronically in the field, the automation for collecting and distributing them was local. Coordination between the different management teams and their computer systems occurred manually by phone and e-mail.

This manual intervention allowed slight, but expensive errors to creep into the data. The southern region produces 1.52 million barrels of crude oil a day, which is 43 percent of Mexico’s total production. Because this volume is worth about $3 billion, measurement errors as low as 1 percent can translate easily into millions of dollars. “We needed an integrated and low-cost monitoring system that would enhance coordination between these teams and take advantage of existing measurement systems,” says Martin Fernandez Corzo, automation specialist at PEP.

As a first step, PEP engineers linked the 12 key remote workstations collecting information from the measurement devices, programming each to run an OPC (an open connectivity standard) server appropriate for the connected devices. “We developed a LabView DSC (for Datalogging and Supervisory Control) application for each of the stations that display the variables’ real-time values and historical trends,” explains Corzo. “These data are then connected to PEP’s intranet, so the variables can be published on the network through the LabView DSC Tag Engine.” The central station sorts through 3,000 tags to monitor all operating variables reported by the local stations.

Not only does the integration of these 12 stations allow management to make decisions more quickly, but it also improves the accuracy of the communications between the different supply and distribution centers. For this reason, management is considering how it might add more stations to the monitoring network, and make its world a much smaller and more profitable place.

For a look at the security part of SCADA systems , check out the article at www.automationworld.com/feature-4222