A powerful programmable logic controller (PLC) is the super-fast “nervous system” of an automated storage system – the vital link between software and intralogistics system. The PLC transmits the machine states to the materials flow software and the warehouse management software in a fast and secure manner and ensures that instructions coming from the software are directly converted into the necessary operations of the storage and retrieval machines and the conveyor technology.

Westfalia Terra Automation, our control systems business in Bremen, Germany, has its own in-house expertise for building and programming PLC systems. This means we can guarantee that all our intralogistics come from a single source, are “Made in Germany” and are immune to bottlenecks in global services and supply. This is not only safer for your company – it is also more cost-effective.

First-Class Hardware, Software and Expertise

No two warehouse systems are the same. We focus all our know-how on your specific system. Our high-quality assemblies are consistently equipped with state-of-the-art, fast, and powerful CPUs. Also, we believe in employing our own experts to get things done.

Our experts develop, produce, program and install control systems that are tailor-made for each specific warehouse layout. They install and program interfaces for seamless processes, using our high-performance warehouse execution system Savanna.NET®, or alternatively, the third-party software that you use for materials flow control and warehouse management.

Our IT experts and service technicians put new systems into operation and modernize existing systems, whether these be from us or from third parties – naturally with a minimum of system downtime and with extensive testing. Thus we can ensure the greatest possible availability of your partially or fully automated warehouse system.

What is a PLC?

A programmable logic controller or PLC is a digital electronic device with a programmable memory – like a PC that specializes in control tasks. The system uses sensors and actuators to control plants in industrial applications.

As digitalization moves towards Industry 4.0, PLCs are replacing hard-wired control systems. PLCs have a decisive advantage: Control is performed via software and via a customized program. PLCs are precisely tailored to fit processes, can be flexibly adapted to new tasks, and can also be extended by adding further modules. And they have even more advantages over hard-wired systems:

  • Suitable for complex tasks
  • More compact
  • More reliable
  • Capable of connecting to additional IT systems
  • Components often less expensive; more cost-effective in the long term
  • Remote maintenance and online access possible
  • Faster fault analysis
  • Lower power consumption
  • Less time-consuming chance of function


All this makes PLC programming eminently suitable for automating production systems, machines, and logistics and warehouse systems.

How a PLC Works

The components of a PLC are inputs, outputs, operating system, and interface. A programming port is used to load an application program which defines how outputs are to be switched based on the inputs and the programmed logic.

The inputs have sensors connected to them. In automated warehouse systems, these are mainly position sensors to detect, identify, and measure distances, to safeguard access and to protect against hazards, e.g. in the form of protective light barriers. The input cards read out the states from the connected sensors and pass these readings to the application program.

The materials flow control and warehouse management software helps save resources by computing the shortest route for goods, from their entry into the system through storage and removal to order picking and shipment. The software also includes an option for automated preparation of trucks for transport. The software passes this information to the PCL program in a predefined telegram format. The program switches the PLC’s outputs so that the logistics system works based on the computation done. Connected to the outputs are the actuators such as electrical valves, contactor controls for electric motors or drive control modules.

The Hub of Complex Intralogistics Processes

PLCs are ideally suited to automated intralogistics. Sophisticated automated warehouse and logistics systems provide numerous storage and retrieval strategies depending on the situation and the machine states. If any individual storage and retrieval machines, vertical conveyors, transverse transport vehicles, or continuous conveyors require maintenance work, the warehouse execution system provides extensive special strategies for storage and retrieval. This means that an automatic high-bay warehouse can continue working efficiently even if individual parts break down or require maintenance.

A powerful PLC system is able to handle the complex and closely interlinked intralogistics processes required by the software and convert them into the appropriate output signals for the warehouse technology. At the same time, the PLC supplies the real-time data required for visualizing and controlling live operations, or for a digital twin, in order to optimize processes, perform remote maintenance, and prepare for modernization.

Modular PLC or Compact PLC?

Modular PLCs are put together to fit the complexity of the processes to be controlled. A central assembly with the processor, input/output components and special components, plus further modules, are connected to one another and scalable.

Compact PLCs already include all the components and are usually less expensive because they are standardized. Also, they can be extended by adding further components. The PLCs in the Siemens Simatic S7 are among the best known. The obsolete Simatic S5 control is often still in use, but involves the risk of system downtime, as the manufacturer discontinued the production series some time ago, so it can be difficult to source spare parts. By using an up-to-date PLC, on the other hand, we can integrate even older existing plants into a modern IT infrastructure.

Do you have any questions regarding PLC programming and PLC system construction? If so, we look forward to hearing from you – contact us at any time for free, non-binding advice.