Integration of panel-mounted process controllers with RS-485 communication and process control software has allowed a small pasta manufacturer to upgrade a SCADA-based operation at minimal cost.

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Strands of spaghetti are visible in the extruder area at the beginning of the pasta process.

Deseret Pasta in Salt Lake City, Utah, owned by a nonprofit entity, produces pasta products for humanitarian relief efforts. A small staff of full-time workers at the plant is supplemented by volunteers from the community during peak times.

When planning an upgrade to its existing SCADA-based operation, cost was a strong issue in choosing a solution. The plant staff desired minimal changes to the current controls but but wanted the benefits of a centralized solution. After considering the alternatives, National Instruments’ LabView was chosen because it offers a graphical environment that can be programmed and customized quickly. The addition of a cabinet-mounted, desktop PC with serial interface and wiring between controllers was the only required hardware to complete the solution.

To simplify development for the pasta maker, the program incorporated process controller communication libraries developed for LabView by Integrated Pro, a developer of custom engineering and programming solutions. The libraries support many commonly available DIN-sized process controllers. This permitted faster development and the ability to add or change features in a drag-and-drop programming environment.

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Spaghetti hangs on bars as it enters the dryer.

The pasta-making plant has two productions lines: one for “short goods” such as macaroni and the other for “long goods” such as lasagna, spaghetti and linguini. Pasta is extruded through a die that is supplied with dough from a mixer-hopper, where Semolina flour and hot water are combined. Different dies in the extruder determine the type of product manufactured. After being extruded into the desired shape, the pasta hangs on long bars as it moves through the dryers. At the end of the drying process, the dried pasta strands are carried by a belt through a cutter, cut to packaged length and delivered in chutes to workers who place the pasta in bins until it is packaged.

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Pasta production runs can be compared graphically for training or diagnostics.

The pasta dryers require control over temperature and humidity in multiple stages as the pasta cools and dries. Each dryer is controlled by two panel-mounted controllers with 4 to 20 mA current loop sensors and voltage-controlled actuators to control temperature and venting. An upgrade to the process, a panel-mounted counter, provides tracking of each bar of pasta through the dryer.

The program trends temperature, humidity and dewpoint values at different locations. The operator can control setpoints and recipes, arm and acknowledge alarms, and view both process history and product drying history for each bar of pasta. Data is saved to disk for offline analysis using custom formatted reports in Excel using a reporting toolkit for LabView.  

“It’s not as simple as Play-Doh,” says one employee. “Pasta drying is a complex process that happens on the molecular level.” Incorrect drying conditions can lead to fractured product or undesirable texture.

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Process control libraries simplify the development of RS-485 communication-based networks in LabView graphical programming environment.

Having a centralized view of the drying process provides an improved picture of how the product is progressing and allows for better control. New employees can be trained more quickly because they can view the process as a whole. Ultimately, the plant makes better product and reduces waste because of the program.