Pick-by-Scan (also Pick-by-MDT)

The picking method Pick-by-Scan is a paperless picking process that is supported by a portable data collection terminal, PDT for short. The PDT replaces the classic picking list in paper form. Mobile handheld computers with integrated 1D or 2D barcode scanners are used to guide the employee step by step through the individual pick positions.

During the picking round trip, the handheld computers can either be held in the hand or connected to a transport system (e.g. a trolley). . Orders and information on pick positions are provided via the device. The order data can either be stored locally or made available dynamically via a network connection from the warehouse management or ERP system.

If the data is stored locally, the tour and the order data must be transferred to the PDT in advance at a central interface to the order pool. Disadvantage: replenishment requests or inventory corrections are stored on the device and are not transferred to the host or warehouse management system until after the tour is complete. Nowadays, an PDT is usually connected to the local network and, as mentioned above, receives orders directly from the WMS. A PDT in the network can also react flexibly to ongoing developments or can be used to respond to current situations.

Pick by MDE im Lager von Emil Frey
The portable data collection terminal, PDT for short, guides the order picker directly to the individual orders. (Image: TUP)

Pick-by-Scan in practice

The storage bin and the quantity to be removed are shown on the display integrated in the MDE. Depending on the system configuration, either each removal must be scanned or the system scans once and the total quantity is acknowledged once at order completion. At the item’s storage location, the picker scans the storage location number and item number. In this way, incorrect picking can be avoided.

Pick-by-Scan - der MDE erfasst den Code und kann so via
Pick-by-scan or pick-by-MDT is only possible with the barcodes provided for this purpose. These are usually attached to the storage location, storage compartment and the inventory itself. (Image: TUP)
Pick-by-Scan - MDEs in der Ladestation - eine Ladung hält in der Regel eine Schicht von acht Stunden.
Two MDTs in the designated charging station. The battery usually lasts between six and eight hours. (Image: TUP)

To avoid picking errors, target/actual differences are displayed again after each scan of the respective order. Once all pick items have been processed, this is communicated to the warehouse management system or the ERP system automatically or by manual triggering. Packing lists and shipping documents are then printed automatically. The actual inventory comparison (see Inventory management) takes place either promptly or at the end of a picking shift.

Advantages of pick-by-scan (MDT) compared to pick-by-paper

  • Real-time communication via WLAN
  • Reduction of unproductive time. No need to manage, print, scroll, read or search for pick lists
  • No need for subsequent inventory comparison
  • Direct feedback minimizes picking errors
  • More transparency (pick data can be displayed graphically by the control center, for example)
  • Targeted guidance during the tour
  • Saves on printers and paper
  • Use in different warehouse areas

General disadvantages of pick-by-scan (MDT)

  • In contrast to pick-by-voice or so-called ring scanners, the employee cannot work ‘hands-free’ when scanning
  • Incorrect reading possible due to dirty or illegible labels/barcodes; the reading process was started but no label could be decoded.
  • Possibly more time required due to multiple scanning (system-dependent)
  • Investment costs – up to 2,000 euros per device (plus additional system and training costs)

Summary of pick-by-scan:

Pick-by-scan is used in many distribution centers and has often replaced the paper pick list. As modern MDT terminals are equipped with WLAN, a keyboard, a display/touchscreen and an integrated scanner, picking rounds can be carried out paperless. The picker can directly confirm pick positions, transmit stock shortages to the system and, if the system configuration allows it, interact with the warehouse management software.

Further information on the subject of barcodes, scanning and picking can be found under Picking – Process steps and under The barcode – EAN, GTIN and GS1 standard.

Pictures within text: TUP