System structure of a Pick-to-Light system

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

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 worldwide unique hardware address. The address is stored 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 established in the system structure. This means that a controller can address not only displays but also subordinate controllers. The system thus 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 completed or not. Depending on this, the command is processed or forwarded to the lower level (further controllers or Pick-to-Light compartment displays).

The management of the structure and its address chains is handled by the software in the LUCA-Server . To enable simple addressing of the hardware components, a logical address (alias) has been inserted.

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 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 operates in a cascaded polling mode. Each controller (parent) checks the status and feedback of its subordinate components (children). To map the structure, each controller thus holds all the hardware addresses of its children, which it constantly polls.

Continuous polling of the structure relays 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 (independent of the structure level) is given a logical address. The WMS controls the display via this address (storage location designation).

What happens to the system structure when a display or controller needs to be replaced?

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

Many years of experience in paperless order picking