A leading seed specialist in Germany, KWS Saat SE KGaA uses state-of-the-art plant breeding methods to increase yields and improve the resistance of plants to diseases, pests and abiotic stress. This requires the seed to be propagated and processed under controlled climatic conditions to high quality standards. In its sugar beet seed production facility at its Einbeck site, KWS prepares the sugar beet seed in a highly automated, multi-stage process. The seed is transported fully automatically into boxes between the individual process steps, and stored in a dynamic high-bay racking system.To ensure seed quality, the temperature inside the storage boxes has to be measured and monitored accurately.
The seed must meet requirements for tolerance to various diseases or drought. The relevant data is exchanged and processed in the system between a server and the controller. “If silo data were lost due to a control system failure, it would not be possible to track which seed is stored in which box,” says Christian Fricke, technical innovations team leader at KWS. “We would have to dispose of the seed that could not be identified. For a high-priced product that can’t be reproduced quickly this is obviously not desirable.”
The warehousing system requires maximum availability and data security. Profinet-based systems can be designed for this task with a redundant controller, referred to as S2 redundancy. With Profinet S2 system redundancy, Turck’s compact TBEN RFID interfaces for highly available systems meet this requirement. In the event of a controller failure, a parallel PLC takes over the process control automatically without any loss of data.
A robot takes over the dynamic removal and placement of the boxes on the appropriate shelf location. The new solution has contactless power and signal transmission. “In the previous system, signal transmission was via contact pins underneath the box,” explains Fricke. “Any contamination on the contact pins or inaccurate placement of the boxes on the pins caused downtime.”
Turck’s RFID solution provides RFID tags at the bottom of each box, with an attached sensor element that measures the temperature inside the storage container. Each shelf location is equipped with an RFID read/write device that reads the tag on the box as soon as it is stored. The read/write device supplies the temperature sensor with power via the voltage induced in the tag. This eliminates the maintenance effort required with a battery-powered solution.
The boxes are managed by the control system of the high-bay supplier. At the same time, a process control system receives the booking telegrams from the controller. For example, if a box is moved to a new position, the process control system updates the entries in the database. “The storage system remembers where a box was stored,” says Fricke.
RFID technology enables unambiguous and complete monitoring of all boxes during transport and storage. The ID stored on the RFID tag under the box can be used to check whether the box is at the correct shelf location. If there are any discrepancies, a stock reconciliation is carried out. The RFID system thus provides the basis for verifying the database information. “This is the perfect solution for us,” says Dr Joris van Dort, technical innovations manager at KWS. “The measured values are transmitted wirelessly and the storage boxes are identified without contact.”
A key requirement for the new system was the avoidance of the complex geometry of the old system, and its large cabling and wiring overhead. Turck’s RFID interfaces stand out here with a feature that is unique in the market: HF bus mode. This function allows the connection of up to 32 HF write/readers per port. In applications with many write and/or read positions, this considerably reduces the wiring effort and the costs. Temperature values and IDs are read cyclically.
This makes it possible to implement continuous temperature monitoring. The read values can also be assigned to the containers at any time. “HF bus mode enabled us to install the RFID read/write devices for a rack without any major effort,” says Fricke. “We just had to connect the pre-assembled cables with T-pieces.”
A major benefit of the Turck solution is the automatic addressing of the RFID read/write devices. After connecting with the T-pieces, the devices are automatically assigned addresses which are activated in the web server. If a device is faulty and has to be replaced, the TBEN registers which read/write device is missing when it is removed. If a new module is connected, it is automatically assigned the address of its predecessor. It is no longer necessary to store preconfigured replacement devices or carry out any time-consuming addressing of replacements for service tasks.
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