Put-to-light in order picking and sorting

Put-to-light order picking
Put-to-Light as the second stage in two-stage order picking

Put-to-Light is a method for sorting goods with the help of illuminated compartment displays. The light signals on the put walls help the order picker to quickly find his storage compartments. The Put to Light system uses the same shelf indicators as the Pick to Light system.

How does Put to Light work in order picking

Before starting, a batch of orders is compiled in the warehouse management system (Multi-Order-Picking). In a two-step picking process, the goods are first picked from the warehouse in several totes. The totes are then brought to the sorting station and distributed to several orders with the Put to Light system. Depending on the solution, there are two different processes in the sortation:

1. put to light sorting with the same articles

If the picking system picks into the totes according to type, then there are always the same articles in a tote. For the distribution of the goods, it is sufficient that the bin barcode is read. Then the system switches on all the compartment displays on the sorting rack with corresponding quantities.

The order picker confirms the placement of the items at the acknowledgement button. This method is only used for small numbers of products.

2. collection boxes

In the first stage of picking, different items are first picked into the collection box. When the goods are distributed, the employee must read each item again and sort them separately. The acknowledgement at the acknowledgement button is identical. This procedure is slower than the first, but gives more flexibility with a large range of articles.

Entering the quantity in the Put to Light process

With some solutions, the items in the box can be grouped very easily (e.g. CD, DVD, etc.), which means that they have to be removed in groups rather than individually.

In this case, the number of items can be entered on a screen of the sorting station. When the items are sorted, the barcode only has to be read once. This saves a lot of time and money during sorting.

Sensors during acknowledgement

To improve the performance and quality of the sorting, sensors are also optionally used on the compartment displays. They automatically acknowledge the placement of the items in the sorting compartments, providing feedback to the position management system without pressing the acknowledgement button. The increase in performance when using sensors is approx. +15%.

What is important in a put-to-light system?

The most important thing with a Put to Light system is the reaction time after reading the barcode. The picker must not wait for the light of the compartment display. From our experience, the response time of the system must not exceed 250ms. Our communication server (LUCA-Server) guarantees the corresponding response times without any problems.


The biggest advantages of put-to-light picking include:

  • Quick orientation of the employee due to the illuminated compartment displays (short search time)
  • Direct display of the number of pieces on the storage compartment (target compartment)
  • Direct acknowledgement of the deposit at the acknowledgement button or sensor and direct response to the warehouse management system
  • Fewer errors, more performance


However, the procedure also has some disadvantages:

  • Low flexibility due to the fixed batch size (number of storage locations)
  • Relatively high investment costs (as with pick to light)


Put to Light solutions are procedures in two-stage paperless picking, in which sorting takes place in the second stage with illuminated compartment displays. In this sense, it is a reverse Pick-to-Light process in which the items are not picked, but put according to the light signals. Read more about put-to-light on Wikipedia or contact us to learn more. We will be happy to advise you.

Many years of experience in paperless order picking