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System structure of a Pick-to-Light system

The logical structure of a Pick-to-Light system is very clear and is divided into several hierarchical levels. In this article, we explain the individual levels and show you how flexible and varied the structure can be.

Different types of addresses in the system structure

A large Pick-to-Light system can consist of several thousand displays. Each display and each controller has a globally unique hardware address. The address is saved during production and cannot be changed.

The hardware address as the basis of the system structure

The fact that each system component has a unique address means that hierarchical levels can be created in the system structure. This means that a controller can address not only displays, but also other subordinate controllers. The system therefore forms a cascade with several levels.

The individual devices are identified and controlled via the address chain. If a component recognizes its own address, the system checks whether addressing is complete or not. Depending on this, the command is processed or forwarded to the subordinate level (further controllers or Pick-to-Light compartment displays).

The management of the structure and its address chains is controlled by the software at LUCA-Server . A logical address (alias) has been added to enable simple addressing of the hardware components.

The logical address

The logical address is a unique name (alias) of the Pick-to-Light component and is independent of the system structure. Usually, the logical addresses of the Pick-to-Light compartment displays are used as the zone name + storage location (e.g. Z01-A12-E02).

Each Pick-to-Light compartment display is given a unique name for control by the warehouse management system.

Feedback in this hierarchy

The entire Pick-to-Light system works in cascaded polling mode. Each controller (parent) checks the status and feedback of its subordinate components (children). To map the structure, each controller therefore holds all the hardware addresses of its children, which it constantly polls.

The permanent polling of the structure forwards the status and feedback to the higher level up to LUCA-Server .


Does the warehouse management system need to know the system structure of the Pick-to-Light system?

No. The entire structure of the Pick-to-Light system is mapped and managed in the LUCA-Server . Each Pick-to-Light compartment display (regardless of the structure level) is assigned a logical address. The WMS uses this address (storage bin designation) to control the display.

What happens to the system structure if a display or controller has to be replaced?

When replacing a Pick-to-Light display, the new display is given the same logical address and the storage compartment can be controlled exactly as before. When replacing a controller, the addresses are simply rewritten automatically when the system is started.

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