Classical automized warehouse- and conveyor installations are controlled by a Programmable Logic Controller (PLC). These PLCs take over the execution of transport orders which are sent by the subordinate system via interfaces.
The subordinate system controls the bin location management, the stock of materials and the orders - futhermore the storage and retreival strategies and the management of instruction deliveries to the PLCs in the form of telegrams.
The subordinate PLC system - e. g. warehouse management or material flow computer - contain interfaces to all other systems. This so-called "Middleware" causes expenses which could be avoided if the SAP system could communicate directly with the PLC.
