By Jim Montague, Executive Editor
It's not the Holy Grail, but it's close. Ever since control and automation engineers began to move away from point-to-point, 4–20 mA hardwiring and toward twisted-pair fieldbuses, Ethernet and wireless, they've been approaching the means to create the one network that can do it all. This is logical because if you had to implement multiple separate networks for controls and automation, power, safety, physical security, administration and enterprise and other special functions, you'd no doubt prefer—if you had the chance—to install one network infrastructure that could handle all these jobs.
Unified Network from Scratch
Besides saving power and costs, the real benefit of a truly combined industrial network is that it can improve plant-floor control and help users run their applications more productively.For instance, pre-packaged food manufacturer CS Vacuum in Milan, Italy, recently needed a new control system that could bring together its modular production line for cooking, dosing, vacuum sealing, pasteurizing, storing and dispatching its meals and enable these steps and its operators to cooperate efficiently. The company reports that its old controller was inefficient because the line's individual production plants didn't have a network to communicate with each other. CS Vacuum also needed a two-part integrated system for controlling the production line and its complex air-conditioning system. The system also had to be as automated as possible to allow CS Vacuum's operators to focus more time and effort on recipe preparation.
CS Vacuum sought assistance from system integrator Apollo Solutions (www.apollosolutions.it) in Pessano con Bornago, Italy, and its controls division, Saguaro Sistemi (www.saguarosistemi.it). To provide the controls and cooperative network that CS Vacuum needed, Apollo Solutions decided to implement a PC-based control system built around an embedded PC, panel PCs and other equipment from Beckhoff Automation.
"One superior, centralized control system is the best way to make all components play as an orchestra with excellent performance and reduced power consumption. Using standard communication lines such as LAN, CAN, Modbus and others permits the interconnection of several subsystems and lets us better manage subcomponents on the same machine," says Marco Brunazzi, Saguaro Sistemi's development engineer. "We also use advanced algorithms as the ideal way to make machines work in the best way possible, such that only the components that are needed are used at specified times and always at the top of the curve."
In essence, the embedded PC controls the scales, cooking pot and the fryer via Modbus, as well as controlling the oven via Profibus. Another unit archives the resulting data, not only for a possible subsequent inspection by local health authorities, but also to verify production performance and efficiency. Also, production is controlled via the local server. Once a particular day's program/recipe—such as spicy chicken—is entered, the specified program is adopted automatically by all plant modules, including the cooking pot, scales, oven, vacuum device, packaging and labeling machine and discharge conveyor (Figure 1).
The panel PCs, which are used for production preparation, are equipped with touchscreens and communicate wirelessly with a local access point. These touchscreen panels are mounted along the entire production line and allow CS Vacuum's operators to monitor each production phase and make corrective interventions as needed.
Meanwhile, the second part of its integrated network controls the production process and the facility's specialized air-conditioning system, which includes four air-treatment units, six fans, two cooling units, water heaters, pumps, overheat switches for the automatic or manual pumps and de-icers for the cold rooms. All consumers in the air-conditioning system are connected to an additional embedded computer.
"Because less consumption means a lower impact, our integrated system manages the various machines in the plant, making all of them work at the highest performance, wasting the least energy possible, all while delivering positive economic returns," explains Brunazzi. "A first-class control system and network allows users to check machine status in real time, including the energy consumption, and view warnings when this consumption rises too much or too fast. This permits the reduction of overall power consumption and cuts energy use, especially in areas that are noncritical in that moment of the production cycle."