Customized connection of a Pick-to-Light system

The software for the customized connection of a Pick-to-Light system, is very often used in plants where the warehouse management system cannot directly control the process. We explain exactly when the interface must be specially built.

Different types of customized connection of Pick-to-Light

Pick-to-Light, as a subordinate system, must control the compartment displays according to the specifications of the warehouse management system. If the software of the warehouse management system is too slow or not flexible enough, the standard interface cannot be used. In this case, the complete picking orders must be transferred to the Pick-to-Light system. The requirements for the interface are very different here.

The compartment displays light up in a standard process as soon as the order is activated. There are different methods to start a picking order. They must also be taken into account in the customer-specific connection, because in that case the Pick-to-Light system is responsible for activating the picking order.

There are several options for custom connectivity.

Connection via a database table

For simple systems that do not need any special functions, a shared database table is sufficient as a customer-specific interface. Both the warehouse management system and Pick-to-Light, access the same tables and thus exchange the data and status values. One or more tables can be used.

The higher-level system enters the order data in the table and sets the order status to "unprocessed". The lower-level Pick-to-Light system can read the open orders and start them accordingly.

Once the withdrawals have been made and confirmed at the acknowledgement button, the Pick-to-Light software enters the corresponding withdrawal quantities and the status values in the table. The warehouse management system then accepts the values and immediately carries out a stock correction and the order posting. Here is an example with two separate tables:

  • Order header:
    • Order number
    • Type of packaging unit (box type, pallet, container, etc.)
    • Number of picking positions
    • Status
  • Order item (multiple records per Picking order)
    • Order number
    • Position number
    • Withdrawal storage bin (storage bin)
    • Withdrawal quantity (target number of pieces)
    • Withdrawn quantity (actual number of pieces for confirmation)
    • [Optional: serial number, batch, weight, etc.].
    • Status

Advantages of the connection method: A simple way of customer-specific connection, where the data structures are mapped directly in the database table.

Disadvantages: No optimal communication in special cases, such as correction of withdrawal quantity and alternative storage bins. No possibility for batch changes or feedback of zero crossing messages(container has become empty). The suppliers of the warehouse management systems often refuse to provide the tables.

Customized online software connection via TCP/IP socket or REST interface.

To realize more flexibility and high performance of customer specific online connection, special connections are realized via TCP/IP socket or REST interface.

In both variants, these are telegrams that are integrated in the software of the two systems. With the TCP/IP socket interface, in addition to the user data, the simple and secure transmission protocol is also integrated. The data contents can be connections with both methods.

Advantages of direct online connection: Very fast and direct communication with any content for special applications with complex processes.

Disadvantages: Relatively costly implementation and complex commissioning.

SAP interface with special formats

For some years now, the RFC method (Remote Functions Call) has been used for customer-specific connections of the Pick-to-Light system with SAP. After coordinating the data structures, the functions are registered and the calls are started.

Data exchange takes place via the internal SAP connection mechanisms (libraries). We have made the experience that the best results are achieved by two asynchronous connections. One for the transfer of the pick list, the second, for the confirmations of the picks.

Advantages of the customer-specific RFC connection: The software establishes the connections automatically and works directly online, without very much implementation effort. The data contents are transferred quickly and securely.

Disadvantages: Relatively complex configuration and commissioning incl. simulation of jobs. Very often test systems are used, making commissioning very complex.


The customer-specific connections of a Pick-to-Light system are used when the standard interface cannot be operated directly by the warehouse management system. In some cases, the reaction speed and the complexity of the process flow are also decisive. The picker must not wait during the picking process. Our software guarantees very short response times thanks to the very fast LUCA communication server.

Many years of experience in paperless order picking