Pick by Light : the ultimate guide

Pick by Light is a very fast and error-free method for picking in a warehouse. A display is mounted on each storage compartment for this purpose. After the order has been activated, the displays light up accordingly. This enables the employee to find his storage compartments very quickly and confirm the activity directly. But why is Pick by Light so special? What distinguishes Pick by Light from the other picking systems? How is a modern Pick by Light built up? Where is the system best used and what are the costs? We will give you the answer to all these questions.

In this and many other blog posts, we'll explain how you can use the Pick by Light correctly plan and implement. Not only do we give you a few tips, but we also explain exactly how you can increase the performance of your order picking and minimize error rates at the same time. Follow our contributions via email mailing or on social media. Here you will find our Pick by Light Displays:

Pick by Light for over 20 years

Let's start first ...
In 1988 Udo M. was a young logistician of a pharmaceutical company and had to improve his dispatch warehouse. There were many problems with performance and quality, but the computer technology at that time was already very modern. Paper lists and ballpoint pens were the only aids to picking.

Udo described the problem to his good school friend Rainer. A few weeks later Rainer K. (young electronics engineer from Iserlohn) decided to develop the first "Paperless Order Picking". Udo was very enthusiastic about the idea. A large Pick by Lightsystem with many displays. The displays should indicate the withdrawal quantity directly at the storage compartment. No more paper lists and no more pens! "Simple and brilliant!" said Udo.

So the first Pick by Light with more than 2.200 displays was created, but the task for Rainer and his team was not as easy as they had been thought. But it worked. The performance of the system has increased significantly, as the error rate, has fallen to almost zero. Do you want too? ... then you've come to the right place!

What is a Pick by Lightsystem?

For the newbies a short instruction before we start with the details. Pick by Light is a complex system and supports employees in picking goods in a warehouse. Imagine a warehouse with many shelves and storage bays. Your articles are also stored there. An electronic display with buttons is mounted on each storage compartment. A computer system controls your order picking. There are no paper lists and no printers. The corresponding Pick by Light Indicators light up as soon as picking is activated. Large LED signals the storage compartment from a distance. The required quantity lights up on the display. The order picker removes the goods from the storage compartment. A direct feedback to the warehouse management takes place as soon as the button is pressed. The display switches off if the withdrawal was posted.

In the display gallery you will find our currently available displays. Further general information can be found at: https://de.wikipedia.org/wiki/Pick-by-Light/

Where is it Pick by Light used?

The system is very versatile. The Pick by Light Hardware itself serves only as display and input devices. The entire logic of the control system, as well as the process itself, can be found in the LUCA-Server is taking place. As a result, the solutions are very flexible and cover a very broad spectrum of tasks. Customer-specific adaptations are possible at any time. The following industries have been successfully using the Pick by Light:

  • eCommerce: order picking and replenishment
  • Automotive: sequencing and picking for the assembly lines
  • Production: workstations, set formation and machine assembly

Pick by Light is used wherever simple information is required directly on storage compartments or on machines. The operator can make appropriate entries via various keys on the displays. The difference between a simple display and a Pick by Light system is due to the fact that with Pick by Light several thousand displays can be used simultaneously. Communication takes place via a professional BUS system. A correctly designed BUS system is suitable for the Pick by Light systems are crucial.

Some manufacturers still rely on PLC controls with ASI-BUS, which is very outdated. This makes the solutions very inflexible. The new standard of the Pick by Lightsystems is called: PTF.

In further blog posts we will report in detail about the individual industries and their specific requirements.

Picking areas

You are in a large shipping warehouse where several areas are to be found. The larger the bearing, the more structures they should recognize. You see different employees picking different orders at the same time.

This is precisely why it is necessary to divide the warehouse into several picking zones. Each zone processes its own partial orders. The Pick by Lightsystem is also divided into logical zones. The structure of the hardware will be dealt with separately later. First of all, this is about the logical division. Then we'll worry about the hardware.

How large can a picking zone be?

Basically the question cannot be answered so simply, as far as further facts are not known. The size of the picking zone depends on many factors, so only a thorough analysis can give the correct answer. The most important thing is that the employees keep a very good orientation. Access to the goods should be fast and targeted. The quality of order picking must be as high as possible.

The system must be supportive for the employee and not disruptive.

On a semi-automatic picking system with conveyor technology Pick by Lightand flow racks, the picking zones are approx. 6-8 m long. The conveyor technology also serves as a buffer, whereby the correct distribution of the goods in the zone is achieved by A/B/C analysis. It is very important that the employee keeps a good eye on all the lights and has the shortest possible walking distances.

For completely manual systems with picking trolleys, the size of the picking zone varies greatly. Sometimes the zones are very long and are even served by several employees at the same time. You'll learn how to do this in a moment ...

Fast navigation

A single order picking zone can also contain several hundred Pick by Light displays. Sometimes, the order picker also has to move his back to the Pick by Light (B or C article). In order to keep track of the storage compartments, special displays are used for fast navigation. At a glance, the order picker can see where the active storage compartments are positioned (bottom left, top right, middle or back). This assigns a navigation display segment to each storage compartment. After each confirmation, the Pick by Light controls the navigation display automatically.

In addition to the graphic display of the active orders, the navigation display shows the number of open withdrawals. Practice shows that the use of navigation makes work much more relaxed and faster for the order picker. This results in a total performance increase of approx. 5-7%. The low cost of the function justifies the investment.

May several employees work in one picking zone?

Yes! The answer is clear, inasmuch as the LUCA-Server is used. With our system several employees can work in one picking zone. We have multicolored LED's available at the Pick by Lightdisplays. A separate color is assigned to each employee and their order. The problem of simultaneous access to the compartments is complex, but very well solved by us. In the LUCA-Server a special procedure was developed for the synchronization of editions and accesses to the same subjects.

This procedure enables correct coordination between the individual processes for several employees and orders. Each employee works with his or her own data. However, each process in the picking zone does not send the telegrams directlyPick by Light, but to a synchronization module. The module is then responsible for the correct coordination of access to the common storage compartments.

Do you want to know exactly how that works? The topic will soon be covered in a separate blog article. Stay tuned...

Can the picking zones be divided flexibly?

The function is possible, but very complex. The challenge does not only affect that Pick by Lightitself, but also the warehouse management (WMS) as well as the control of the conveyor technology. Whether the dynamic division of the picking zones is really practicable has not yet been answered with a clear "yes". We always examine these requirements very thoroughly and precisely before such plants are built. We have already developed many variants of the solution, but almost every solution was very customer specific. Some examples of these will soon be presented in our other blog articles.

How is the Pick by Lightsystem structured?

The individual Pick by Lightdisplays are connected to a BUS system via spring contacts, with each display having a unique address. The controller can use the address to distinguish between the displays on the BUS and to control them specifically. One controller can manage and power over 100 displays. All controllers can be connected via LAN to the LUCA-Server connected. In large installations, the controllers are sometimes wired to each other via an internal RS485 bus. This clearly saves the number of LAN connections required. Several thousand storage locations can function simultaneously in such a system. Response times to the individual actions are very fast and are only a few milliseconds. We will present the physical structure in more detail in further blog posts. The KBS display system is especially suitable for this and is fully integrated in the LUCA-Server integrated.

Simple Pick by Light - assembly

At that time in the 90′ years was the Pick by Light Assembly very complex. Each display at that time had its own cable to a small mini controller in the mounting profile. All mini controllers were connected to a large controller via a BUS system. The large controllers were then connected to a PC via many serial interfaces. Very, very many cables ... Today the assembly is fast and simple, so that the costs remain low. Aluminium rails are mounted on shelves or supports. A single 4-wire cable connects the rails to the LAN controller. The Quick-Click system allows the displays to be mounted on the rails very easily and without further wiring. For a perfect connection between the Pick by Light display and the BUS system ensure optimum spring contacts.

... and if drilling is not allowed ?

No problem. In such cases we deliver the subprofiles with strong magnets. The magnets hold very well on the heavy-duty shelving (SLR). Depending on the length and number of displays, we mount a magnet at intervals of approx. one meter. In this case the final assembly takes only a few minutes! After the "click" only the BUS cable with 4 wires has to be connected. It's that simple.

How flexible the Pick by Light installation can be?

Due to the special Quick-Click-System the conversion is very easy. A BUS system is integrated in the aluminium profiles. The indicators are connected via three spring contacts to ensure power and data supply. All you need to remove the displays is a simple tool. No cables and no screws. Then you can easily change the position of the ads. The controller automatically recognizes the displays. For a simple stock transfer within a picking zone, an IT conversion is not even necessary. The display can be easily moved with the goods.

Add new or exchange displays (modules)

Also very simple... A new display is simply clicked into the aluminium profile by Quick-Click. With a small tool (spatula) the mounted displays can be removed from the profiles very easily. The displays can then be configured very easily via a web interface. When you extend the system, the new displays automatically log on to the system. At the beginning each display has the name of its physical address. The configuration is used to adapt the preset designation to the desired designation (e.g. storage location). Replacing the displays is also very easy. Only the physical addresses of the replaced displays are exchanged. The rest happens automatically. The assignment to the zones is also configured via the software. Who can replace or configure the displays? Anyone who is authorized to use the web-based configuration program. No technicians need to be employed for the conversion or expansion.

Pick by Light process flow

Do you know an installation that is exactly the same as the other one? I'm afraid not. Very often the requirements for this Pick by Lightare very different. We integrate various solutions into our systems and very often build the processes to customer specifications. Of course, there are comparable sub-processes as with any solution, but customer requirements outweigh standardization. All logical data processing is performed by the LUCA-Server.

Start of picking

There are already several options at the start of picking. But how can this Pick by Lightstart the correct orders? Can the completeness of the last order also be checked? Here you will find the answers to the questions. Basically, there are two different start methods:

  • Start via a document with bar code
  • Paperless picking

If the cartons or totes are marked with a barcode (1D or 2D), you can use a barcode for the Pick by Light activation stationary or mobile scanners can be used. In this case, activation can also take place via the delivery note or invoice. RFID technology is also supported. With paperless systems, the orders usually start automatically, either from a data buffer or by an automatic discharge of the containers via a conveyor system. In both cases, the LUCA-Server the individual processes and ensures the appropriate quality. For some solutions, the start of the next job will only be possible once the previous job has been completed. If an error occurs here, the Pick by Light System displays an error message.

Simultaneous, sequential or pagewise?

If you have already started order picking, the displays should be lit now. But how can they shine best? All together, one after the other, first the one and then the other side of a shelf aisle? Different methods are used to achieve different goals. As a planner, you must understand the exact procedure well and select the correct method. This point is very important when creating the systems. Take your time to find the optimal solution.

Although a Pick by Lightdisplay is very simple in principle, the process can be structured very differently. The control for this is done by a software module on the LUCA-Server. If necessary, different methods can even be mixed (A/B/C). With simple systems, all displays in a picking zone light up simultaneously. That's the standard, too. In other cases, we create a picking route and control the picking sequentially. There are other methods that we will look at in detail in our blog articles later.

Confirmation of withdrawal and end of order

Once all articles have been picked, the employee acknowledges the removal by pressing the button, after which the displays are switched off. The confirmation of the withdrawal triggers a confirmation to the higher-level warehouse management system.


Logistics and production are among Pick by Lightthe best and most widespread order picking solutions. Simple installation and flexible conversion options make the system very attractive. With many storage compartments in large warehouses, however, the price is also high. It therefore makes sense to use the system for the picking of A articles and to support the B and C articles with other technologies.