Customized connection of a Pick-to-Light

Various types of customized connection of Pick-to-Light

Pick-to-Light, as a subordinate system, must control the compartment displays in accordance with the warehouse management system's specifications. 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. 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 various methods for starting a picking order. They must also be taken into account in the customer-specific connection, because in this case the Pick-to-Light is responsible for activating the picking order.

There are various options for customer-specific connection.

Connection via a database table

For simple systems that do not require any special functions, a shared database table is sufficient as a customer-specific interface. Both the warehouse management system and the Pick-to-Light system access the same tables and therefore exchange 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 can read the open orders and start them accordingly.

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

• Order header:
  • Order number
  • Type of packaging unit (carton type, pallet, container, etc.)
  • Number of picking positions
  • Status
• Order item (several records per picking order)
  • Order number
  • Item number
  • Withdrawal storage bin (storage bin)
  • Withdrawal quantity (target quantity)
  • Quantity withdrawn (actual quantity for confirmation)
  • [Optional: serial number, batch, weight, etc.].
  • Status

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

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

Customer-specific online software connection via TCP/IP socket or REST interface.

Special connections are implemented via TCP/IP socket or REST interface to realize more flexibility and high performance of the customer-specific online connection.

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

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

Disadvantages: Relatively time-consuming implementation and complex commissioning.

SAP interface with special formats

For some years now, the RFC method (Remote Functions Call) has become established for customer-specific connections between the Pick-to-Light and 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 found that the best results are achieved with two asynchronous connections. One for transferring the picking list, the second for confirming withdrawals.

Advantages of the customer-specific RFC connection: The software establishes the connections automatically and works directly online, without a great deal of implementation effort. The data content is transferred quickly and securely.

Disadvantages: Relatively complex configuration and commissioning, including simulation of orders. Test systems are very often used, making commissioning very complex.

Conclusion

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