What's Pick-to-Light?

Pick-to-Light describes a paperless picking process in which compartment displays are controlled by a warehouse management system. The pick list is replaced by light signals. After paperless picking, the stock change at the storage compartment is confirmed by the picker with a confirmation button and reported back paperless. A Pick-to-Light system can contain several thousand compartment displays. In the article Pick-to-Light will help you to better understand and correctly apply.

Pick-to-Light Compartment display on the storage compartment is actuated by an order picker at the acknowledgement button. The LUCA system debits the removal automatically.

Pick-to-Light System

The Pick-to-Light system consists of many Pick-to-Light compartment displays and the controllers. These compartment displays are often used in 2021. The complete list can be found below (blue button).

PTF-L-6 - Pick-to-Light Module without display. Only LED and button.

Tray display for removal of individual items without entering the quantity (advantages at Automotive or storage during replenishment). Details of PTF-L-6.

PTF-3N-4 Pick-to-Light Display with three-digit display and keys

Standard compartment display for many applications with numerical input of the quantity. Details for PTF-3N-4

PTF-ZCTRL2 innovative Pick-to-Light controller and display with touch screen

Zone display with touch screen.
Details about PTF-CTRL2

Pick-to-Light made in Germany

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In this article you will find the most important information about Pick-to-Light. You will correctly understand the technical details and correctly use the specialized displays.

Why is the Pick-to-Light so special as a picking system and how high are the failure rates? What distinguishes the system from other picking methods? What is the structure of a modern pick-to-light? Where is Pick-to-Light best used and what costs should you expect? Let's get started ...

Many years of experience in paperless picking

Logistics and Production 2021


The pick list

Like all paperless picking processes, the Pick-to-Light system (also called pick-to-light) processes an electronic pick list. The data is transmitted by the warehouse management system. The picking system supports the picker in his work to minimize his walking distances and picking errors and to optimize his performance at the workstation. The order throughput times are optimal due to the short search time (light signals directly at the storage compartment). Customer orders are picked and processed quickly. The training time for the pickers is minimal with this picking method. 

The acquisition costs are relatively high compared to other paperless picking systems. On the contrary, the costs for maintenance and operation are minimal. As a supplier, we always look for an optimal solution for our customers. We will write in detail about the topic of costs later.

Hardware and assembly

The Pick-to-Light hardware is modular and very flexible. The assembly at each extraction point is very simple. The mode of operation is clearly structured. The light signals are ambiguous to indicate the goods to be picked.

  • Controller (communication and power supply)
  • Mounting rails with integrated BUS
  • compartment displays with signal lamp (2 x 7 colours), quantity display and one acknowledgement button

Almost all compartment displays are equipped with several additional keys to correct faulty stock levels (plus, minus and F key for special functions). Not all compartment displays have the quantity display (only signal lamp and acknowledgement button). The hardware is very robust and has been tested for years.

Mounting rail


  • Sensor for automatic acknowledgement monitors the intervention on the storage compartment (access monitoring).
  • Digital I/O for receiving and transmitting external signals.
  • Beep tone

The hardware of the Pick-to-Light system is controlled in real time by the LUCA software. The connection to the warehouse management system, material flow and conveyor technology is made via LUCA-Server, which controls the entire processes. The system is very flexible.

Pick-to-Light Sensor

The Pick-to-Light sensor has an important new function in withdrawal confirmation. A sensor can be optionally installed above or below the compartment display. The sensor overlaps the accesses to the storage compartment and automatically confirms the actions. However, the goods to be picked cannot be counted with it. The function of the automatic control is based on a light sensor. The exact mounting of the sensor has to be coordinated for the distance. The sensor as a light sensor, can measure 15-20 cm without a reflection mirror. With a mirror, the distance can even be increased to 80-100 cm.

Pick-to-Light and how it works

The principle of the picking system: The picker is in the foreground. In the host system (merchandise management system or WMS) the order entry, preparation and transmission of the individual orders takes place. The warehouse management system prepares the orders (orders for quantities of goods) for logistics.

The paperless pick list with pick locations and quantities is transmitted to Pick-to-Light via a database, file or TCP/IP interface (depending on the application). The order data to be picked from SAP comes via IDOC or RFC. The picking process can begin.

Start and the withdrawal

The Pick-to-Light system activates the required displays at the storage location in the appropriate storage area (picking zone) according to the pick list. The LED lights (indicator lights) and the quantity displays are switched on in the appropriate light colour. The functions are active and picking can begin. The employee (also called picker ) reads the quantity to be picked from the quantity display directly at the pick point (compartment). Additional information is shown on the alphanumeric displays.

The picker confirms the removal (picked quantity) from the storage bin at the acknowledgement button, which causes the compartment display to go out. The confirmation posts the withdrawal (immediate correction of the stock - automatic stock change). The sequence is not important for the system. However, if the picking list defines a certain order, the displays are switched on one after the other.

Once the picker has picked all items, the picking process is basically complete and the stock changes are reported back. The confirmation (feedback) takes place immediately. The shipping units (cartons, pallets, skeleton containers, etc) can be prepared for shipping.

The process here can be very different and customer-specific. In this case 100% customer satisfaction is very important to us. The process is LUCA-Server often individually adapted, whereby the quantity display is switched off immediately or only after the last confirmation on the acknowledgement button.

Material staging is controlled by Replenishment. The Pick-to-Light system can also provide very good support there.

Correcting the withdrawal quantity (plus/minus keys)

If there are not enough products on the shelf(container, wire mesh box, pallet, etc.), the picker cannot carry out the acknowledgement. The operator can correct and acknowledge the error on the order with the correction keys on the quantity display. The new actual quantity is confirmed (quantity corrections). The function key (F-key) gives the picker additional options for a permanent inventory. The operation is very intuitive and requires almost no training of the pickers.

The frequency of the correction is strongly dependent on the quality of the merchandise management system. The entry in the goods receipt and the correct storage of the goods (replenishment) play a decisive role. Some merchandise management or warehouse management systems still leave a lot to be desired. The KBS buttons are very well integrated.

Pick-to-Light activation with a barcode scanner

With a scan of the picking list or the picking container, the picker can also activate the pick order in the picking areas (also for a picking vehicle). Different devices (scanners) can be used in the activation method. The solution with this LUCA-Server is very flexible here.

Pick-to-Light Advantages and disadvantages

The advantages and disadvantages of a Pick-to-Light system can generally not be completely defined. Some features can be clearly defined as advantages and some as disadvantages. Others depend on individual circumstances and situations in the system.

Advantages Pick-to-Light

Pick-to-Light system and the most important advantages at a glance:

  • The picker has hands free when picking (freedom of movement).
  • Optimum operator guidance through the picking list (also on the picking vehicle).
  • Great flexibility thanks to the wireless rail system. Easy hardware installation.
  • Quick conversion options for each display.
  • Very low error rate in picking.
  • Very low susceptibility to errors through the use of proven and error-free technology (automatic acknowledgement possible).
  • Increase of efficiency and productivity through optimized processes (pick and put).
  • Low training effort.

Disadvantages Pick-to-Light

Pick-to-Light system and the disadvantages in brief:

  • Relatively high acquisition costs.
  • Difficult to use with freestanding pallets (special construction required).
  • Cable routing to each rail required.

Where is Pick-to-Light used?

The following industries have been successfully using our Pick-to-Light for many years:

  • eCommerce: order picking, replenishment, sorting station in the dispatch warehouse
  • AutomotiveBatch picking and sequencing of shopping baskets and JIT racks for the assembly lines
  • Production: assembly stations, set formation and machine assembly

The paperless picking method is very versatile and is designed to support the picker and avoid picking errors. The field of application is large. The modules themselves only serve as output and input devices. The entire logic of the control, as well as the process, takes place in oursLUCA-Server .

How good is the picking method?

Performance and quality are opposing parameters. As a result, the more performance is expected, the less quality the order picker can achieve and the error rates increase. Increasing performance and quality simultaneously is not easy with any picking method. Faster and cheaper. That is the goal. The control software's solution is not everything.

As a leading order picking process, Pick-to-Light provides us with an excellent example of how performance and quality can clearly increase quickly and operator guidance is improved.

The performance increases up to 40%. The targeted support of access to the storage compartment also increases the quality by more than 15%. This minimizes picking errors. If sensors are used, the quality increases by another approx. 10%.

When planning the system, it is essential to consider cost-effectiveness and increased efficiency. However, so does the order picker itself. The Pick-to-Light requires a relatively large amount of hardware, which makes the procurement of the equipment not exactly cheap.

A ROI calculation must show whether the investment is profitable for the company. Get in contact with us. We will help you to carry out the calculations and explain the installation.

If the demand for power is not particularly high and the storage space is large, we can alternatively supply other technologies such as Pick-by-Scan, Pick-by-Watch, Voice Picking, etc.


In logistics and production, the Pick-to-Light System as a picking method is one of the best and very common picking methods. The order picker intuitively follows the light signals and quantity displays at the picking location and thus minimizes his search time (operator guidance through the orders). Numeric and alphanumeric quantity displays show the number of articles. Correction keys help in case of inventory errors.

Simple installation, robust acknowledgement buttons and the flexible conversion options make the system very attractive. Simple connection to any warehouse management system via the LUCA-Server brings enormous advantages. The system can also support permanent inventory very well. The aim is to achieve optimum operator guidance through customer orders.

However, in warehouses with many storage compartments the price is quite high. Therefore, it makes sense to use the system for picking A-items and to support the picking of B- and C-items with other technologies. Put-to-Light can also be used on the vehicle with WLAN to optimise picking picking times, travel times, etc.

Which picking method suits your company best?

Further articles on the subject:


Where is the system used?
The properties
The process
Optimal picking
Division into picking zones
Standards and extensions
Build it yourself?

Frequently asked questions

We will gladly answer your questions

How does it work Pick by Light?

Directly at the storage compartments, the compartment displays light up to match the order. The LED signals the position to the picker from a great distance. The quantity display shows him the required quantity. The picker picks the goods and confirms the removal at the acknowledgement button of the compartment display.

How does it work Pick by Voice?

Pick by Voice works differently than all other picking methods. It is based on voice output and voice recognition. The picker hears the commands in a headset. He confirms his pick by voice on a microphone. But how it really works, you can read in the article: Voice Picking.

Many years of experience in paperless picking