Automatic 'hot and spicy' with configurable control

Poco Loco is a Belgian snack food manufacturer from the Paulig Group that engaged Pilz to optimize its production lines and processes. In addition, safety had to be re-examined. The end result was a new zone layout and the use of the configurable small PNOZmulti 2 controller. By using it as a central safety device, consistently good and also safe production of tasty nibbles is a reality.

The portfolio of Roeselare-based Poco Loco is extensive and ranges from chips to dips: different types of tortilla wraps, tortilla chips in the most diverse flavor varieties, complete meal packages, as well as spice mixes and salsas. 

Better cohesive governance

The production process for tortilla chips consists of carefully defined process steps that are aligned in the chain and must be finished precisely. "This caused problems in the past; partly because the plant was controlled decentrally," says SPS programmer Jeroom Verstaete of Poco Loco. "This was because the chain of installations in the production line was installed by different machine builders and also the control of the installation was a combination of different SPS systems and emergency stop relays." 

Because the various machines were considered separate units, for example, each sub-installation had its own emergency stop circuit. As a result, it could happen that they switched off safety zones partially separated from each other. Moreover, when all emergency stops are connected in series in a safety control system, it is often difficult to locate the problem accurately in the event of a failure. This led to long downtimes. In short: things had to change, and the snack manufacturer set itself the goal of achieving more efficient operation in a safe production line. The idea was to convert the decentralized control to a central SPS with decentralized E/A for the individual machines. The emergency stops were to be integrated into an umbrella system and the visualization of the plant, with an immediate clear overview of all production lines, was to be built in.

Final result

The solution to achieve this was found in the small controller PNOZmulti 2 from Pilz. Via the software, each safety component is assigned an unambiguous DIAG (Dynamic Information and Action Gateway) address. This allows direct visualization of where a problem might occur, which simplifies troubleshooting and (larger) problem prevention. Furthermore, the information can be sent to the higher-level control system via a fieldbus system in the context of diagnostics. After completion and validation, the safety program is given a CRC check and documented. Any change made in the interim can thus be quickly recognized. This increases safety against manipulations and in the event of liability, traceability is proven.

In the new configuration, the production line continues to use drives with frequency converters equipped with an STO function (Safe Torque Off). When an emergency stop is triggered, the drive is stopped in a controlled manner via the STO function. In addition, the production line is divided into nine zones so that switching off one zone does not affect the other zone. 

Configure

With the PNOZmulti Configurator configuration tool, technical staff can create a PNOZmulti program and, with sufficient rights, also modify it. In the process, this tool can be used to search for failure causes and make a simple diagnosis of the failure. 

Maarten Dedeurwaerder, project engineer at Poco Loco, also reveals the ease of use in connection with this software version: "The fact that we chose PNOZmulti 2 is mainly due to the simplicity of the configuration tool to be operated. The entire technical department received a half-day training and can now start the dynamic program view, in which the entire safety program can be followed, without any problems. The simplicity is also related to the fact that the tool is highly visual and allows an intuitive way of working. In short: the new solution has made the production process more efficient and safer. Exactly what we wanted."