During the operation of their plants, Bachofen AG from Uster in Switzerland, equipped their box conveyor system with a wireless identification system (RFID) for automatic guidance. Read/write heads are integrated into the roller conveyors, read the data tags that are attached to the bottom of the transport boxes and make the data available via Profibus DP. Thanks to its modular concept with tags, read/write heads and interface components, the RFID system, BL ident, from Turck allows a custom automation solution.
A 3,000 square meter storage space over three stories, a bidirectional elevator system, approximately 350 transport boxes and a stock of mechanical, pneumatic, hydraulic and electronic articles worth several millions of Swiss francs are the key points for the latest automation project undertook by the Bachofen AG from Uster in Switzerland. The family business began in 1945 and offers industrial automation solutions for motion engineering, fluid control and pneumatics, hydraulics, robotics, vision and RFID to OEM and end customers from Switzerland and Liechtenstein. Along with single components, Bachofen's portfolio also contains special branch and system solutions.
Modification during operation
Within the restructuring of the logistics between March and May 2010, the container conveyor system in the storage space was also modernized to meet the growing requirements of the future. "The replacement of the equipment had to happen during operation, so we had to keep the time for modification as short as possible," Walter Landtwing, director of sales at the assigned system integrator Gilgen Logistics AG, describes the task. Further important requirements were the modularity of the transport system and the zero-pressure transport of the boxes. "The old transportation plant was nearly 40 years old and we weren't satisfied with its performance any longer," Kurt Gfrerer, product manager automation of the Bachofen AG, summarizes.
In consultation with Bachofen, the system integrator decided to implement a touchless, wireless identification system in order to organize the transport processes of the goods more efficiently. Although Bachofen is the sales partner of Turck in Switzerland, RFID solutions from different providers were evaluated before the decision was made in favor of the modular RFID system, BL ident, from Turck. "We were convinced by the intelligent design of decentralization, the easy and flexible integration into the already existing controls and the flexibility of the whole system," Landtwing explains. "With the decision for the RFID system from Turck, Bachofen relies on intelligent control technology for their logistics. The decentralized intelligence has the advantage, that the superior controls of complex applications are considerably relieved."
Intelligent transport system
And that's how the transport system works: At one of the three stations, the staff of the warehouse manually assigns a destination at one of the three stories to the transport box via an operation unit - incoming goods, commissioning or outgoing goods. As soon as the box is transported, a special read/write head (TNL R-Q80L400) that is integrated into the runways, writes the destination onto a FRAM data carrier (tag) underneath the box. The read/write head that is used fits exactly into the spaces of the 80 cm wide standard roller conveyor. Now the transport is fully automated.
If the box has to be transported into another story because of commissioning, another read/write head located on the service lift reads the destination at the tag. If all spaces at the destined story are occupied, the box stays in front of the lift until there is free space again. The boxes from the upper stories reach their destination on the ground level in the same way. A third read/write head at the exit of the service lift reads the according target data.
CoDeSys programmable gateways
With only three read/write heads on each story, Bachofen realized an efficient and fully automated destination guidance system - a circle with decentralized intelligence at the I/O stations. First the read/write heads forward the target data of the boxes to the modular fieldbus system, BL67, from Turck. BL67 includes a programmable gateway for fieldbus communication and individual integrated interface modules with numerous advantages: Since the I/O modules are independent from fieldbus and can be replaced during the operation of the plant, the whole communication environment can be upgraded flexibly and adapted to new automation requirements - no matter if more RFID-interfaces, additional sensors or actuators are needed.
By request, CoDeSys programmable gateways (IEC 61131-3) that support the consistent decentralization with additional control and diagnostic functions are available. Bachofen relies on an easy programmable Profibus gateway. "The biggest advantages are the onsite intelligence regarding the data handling and the uncomplicated integration into the controls," Gfrerer explains. "The function module that is needed for the PLC is executed directly in the gateway, therefore the superior S7-control is relieved and only relevant data is exchanged. It couldn't be easier," the automation specialist summarizes.