Wireless communication, smooth palletisation

The transfer wagons of the palletising system, developed recently by a South American machine construction company for a large consumer goods manufacturer, cover a distance of 80 metres

People around the world should be given the opportunity to consume products that are manufactured, packaged and prepared for shipment to the highest quality standards. It is precisely this objective that the South American company is pursuing, and Weidmüller is helping it to develop machines for manufacturing and transporting beverages, food and chemical products. The company attaches great importance to the robust design and smooth handling of the palletised units, in addition to low maintenance costs.
Successfully avoid system disruptions

The machine construction company recently developed a palletising system for a major consumer goods manufacturer comprising a total of ten production lines, each with its own product stacker.

A wagon moves between two end stations within this system: at the first station the empty pallet is placed on the wagon and transported to the stacker. The stacker loads the goods from the roller conveyors onto the pallet, which is then conveyed to the wrapping station. Once the pallet has been set down, the cartons that are ready for transport are wrapped with polypropylene film to protect them during their onward journey.

To allow the wagons to be activated and controlled, communication needs to be maintained with the

Full radio coverage and uninterrupted data transmission over a distance of 80 meters overcome by the transport wagons are guaranteed by a wireless communication solution from Weidmüller

central controller over the entire distance of 80 meters. The moving parts in sophisticated machinery systems like these require state-of-the-art drag chain connecting cables or sliding contact systems. However, the stresses in an 80-metre long drag chain, which could be used in the palletising system above, would be extremely high. To prevent defects, the data cable would have to be replaced on a regular basis. Disruptions to the system caused by wear and tear or maintenance work can be avoided, however, by setting up wireless communications with proven industry components.
On the right track with WLAN modules
“A previous solution comprising slip rings and brushes was more than capable of controlling the movements of the wagons, but was considered too vulnerable for the demands of our customer. Installations with a non-industrial grade wireless solution were also unable to provide the necessary performance and associated reliability,” explains José de Paula from Weidmüller, summarising the experiences that were related to him by his customer.
“The machine company came to us with the explicit request for a wireless solution. The initial test setup with our WLAN module, which can be used flexibly as an access point, bridge or client, was enough to convince the company that we were on the right track with this solution.”
For the application, four servo motors and three converters for each wagon needed to be integrated into the communications network via Ethernet/ IP protocol. Various sensors and valves were also used; these too needed to be centrally controlled.
 Turbo Roaming provides Weidmüller WLAN modules with uninterruptible connections in wireless data communication
Turbo Roaming provides Weidmüller WLAN modules with uninterruptible connections in wireless data communication

As the communication structure was being set up, Weidmüller provided the machine company with detailed advice and worked with it to determine the ideal configuration and orientation of the WLAN module.

A WLAN client is now positioned on the wagon and communicates in roaming mode with two WLAN access points along the route. These are connected to a Wireless Distribution System (WDS) to enable the radio range to be extended fully across the length of the application. This allows the mobile client to continuously test which of the two access points provides the best transmission and reception quality at a given moment.
“At the cross-over point, handover to the transmission and reception range of the other access point takes place smoothly and automatically. The transfer of communication usually takes around two seconds. Our modules accelerate these processes by means of Turbo Roaming,” explains de Paula, pointing out one of the highlights of the Weidmüller WLAN modules. “Depending on the control performance, our solution supports fast changeover times of less than 50 ms when switching clients between different access points. This ensures that the cycle times required by the application can be transmitted flawlessly via wireless communication without any risk of interruption to data communication.”
Stable, uninterrupted data transmission
“During operation we were particularly impressed by the stability of communications. Even though the environment with its many metal fences is a challenging place to assemble a wireless solution, Weidmüller was able to provide us with a completely stable solution,” smiles the Palletisation System Engineering Coordinator. 


“By dispensing with the slip ring motors, cabling, additional filters and special rails that were previously used, we ended up with a structure that is both nonwearing and more cost-effective. In line with our own high standards, we were able to deliver to our customer an efficient overall package for achieving the required product quality and production targets.”
To ensure the smooth commissioning of the system at the end customer’s premises, Weidmüller provided the consumer goods manufacturer with support both during and after the implementation of the palletising solution. Measurements were taken of the action and reaction times of all the Weidmüller modules installed in the machine structure to ensure sustainable high performance.

A WLAN client is now positioned on the wagon and communicates in roaming mode with two WLAN access points along the route

To enable this successful solution to be transferred to other systems, Weidmüller provided its customer with detailed advice and training on possible standardisation and configuration. Equipped with the requisite know-how, the engineers of the manufacturing group are now able to deal with any upcoming projects that require wireless communication.

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Published in November 2013