THE SHOW | THE MICROTECHNOLOGY INFORMATION PORTAL
20.04.2026
C - Automation
ZERO CABINET
The time has come: Out into the field
Is there still a need for control cabinets today? This is a question that many managers in the mechanical and plant engineering industry have asked themselves. The answer can be found in this article, which deals with decentralized automation technology.
For decades, the control cabinet has been an integral part of machine and plant engineering planning. So why is it that it is becoming increasingly less important in the considerations of many design departments?
To understand this, we need to take a leap back in time of almost thirty years. Until shortly before the turn of the millennium, the world was still in order – at least from the perspective of the control cabinet manufacturer! Until then, sensors and actuators were designed using passive technology, and each signal required a cable using 2/3-wire technology. Even outsiders could easily assess the complexity of an application based on the terminal blocks installed in the control cabinet.
However, this approach involved considerable effort and extensive processes – not only for the machine and plant manufacturer, but also for their customers. When making a purchase, they had to carefully consider how to manage the cable harnesses between the control cabinets and machines. Some of these disappeared into floor shafts, while others were laid over massive routes. This had an impact on planning and commissioning times and caused considerable costs.
Decentralized IO modules reduce installation effort
Increasingly complex machine and plant concepts ultimately prompted various manufacturers of automation technology to take action. They considered how they could reduce the installation effort and cable bundles. Their answer: decentralized IO modules. Murrelektronik GmbH from Oppenweiler, for example, launched its first IO fieldbus modules with pluggable connections back in the early 1990s. They bore the cryptic name MSAB, were as big as briquettes, and, thanks to their high IP65 protection rating, reliably collected sensor and actuator signals directly on site.
While mechanical engineering initially didn't really know what to do with this new technology, the automotive industry quickly recognized its benefits. Thanks to the new technology, it was able to save kilometers of cables and routes in its extensive production facilities. It also made service and maintenance easier by simplifying troubleshooting and providing pluggable electrical connections.
This heralded the removal of components from the control cabinet. Although it was still very full, the path toward decentralization had been set. The more daring were already dreaming of the single-hook machine. Their idea was to deliver a machine that was completely ready for operation. Their thinking was that all that would need to be done at the installation site would be to connect the power and data cables, and production could begin. But that was to remain a dream for the time being.
Single-channel shutdown increases availability
However, the desire for higher system availability was not just a dream. Although the decentralized IO modules now collected the sensor and actuator signals in the machine periphery, they initially had a weak point. In the event of an overload or a short circuit, the entire module went into fault mode. None of the eight M12 ports could send or receive signals anymore.
Thanks to their active participation in standardization committees, the managers at Murrelektronik GmbH were aware of this problem. But how could this disruptive behavior of the IO electronics be circumvented? The automation expert from the Stuttgart area proved once again that the Swabians are not known worldwide as “tinkerers” for nothing and presented the MVK in 2001. The Murrelektronik Verteiler Kompakt was the first module to feature innovative single-channel shutdown in the event of a short circuit or overload. Since the remaining seven channels remained operational during a shutdown, this approach increased system availability to an impressive 87.5 percent. At the same time, a red LED on the slot signaled to the service team at a glance where the problem lay.
One IO module for all eventualities
With the increasing acceptance of decentralized IO concepts in mechanical engineering, the number of available IO modules grew rapidly. After all, all eventualities and requirements had to be covered.
However, this multitude of decentralized IO modules soon presented another challenge. For some machine builders, storage costs suddenly skyrocketed because designers had to plan for many unused reserve ports in order to be able to handle all signals on the machine with the common IO modules such as DI8, DO8, or DI4/DO4.
The engineers at Murrelektronik once again proved their creativity and were the first manufacturer to launch multifunctional IO modules. The revolutionary feature was that standardized pins and software configuration allowed users to freely decide whether to use a signal port as an input for sensors or as an output for actuators. This meant that it didn't matter whether they needed two inputs and six outputs or five inputs and three outputs. This multifunctionality created space in the warehouse, as all requirements could now be covered with just one IO module.
Zero Cabinet with Vario-X
With advancing miniaturization and ever-improving power electronics, technical solutions that had previously seemed unthinkable suddenly became possible in 2005. One example of this is safety modules, which made it possible to collect safety-related signals out in the field. Later, decentralized power supplies with high efficiency and high protection ratings were added, which were supplied with 1- or 3-phase power depending on requirements and provided 24 VDC at the output.
The path of decentralization embarked upon more than three decades ago and the possibilities offered by increasingly energy-efficient devices enabled Murrelektronik to make its next significant breakthrough in 2022. With Vario-X, they present the solution for switch cabinet-free machine automation. They integrated the components that had previously remained in the switch cabinet into their flexible and scalable IP67 platform.
These include a powerful IPC with a quad-core processor. This allows computationally intensive components of an application to be distributed across the cores without the need for an additional PC or gateway, thus keeping cycle times short. Image processing, a digital twin for collision avoidance, or special measurement applications, to name just a few examples, can be distributed across the cores.
Two powerful power supplies provide the flexibility needed in the field to easily implement different applications. While 24 VDC is available for external IO modules and other peripheral devices, a 48 VDC connection supplies the drive technology with power. The highlight here: when using motors with integrated control electronics, unshielded motor cables can be used. This eliminates the need for complex connections, such as attaching the shield, as well as the higher acquisition costs for shielded cables.
A feed-in module with integrated main switch, a battery for buffering the IPC, an 8-port IO-Link master module, an Ethernet switch, and a safety PLC with associated safety IO round off the solution and form the basis for decentralized automation concepts.
This is also confirmed by the organizers of the Swiss industry trade fair Sindex, who presented Murrelektronik with the Swiss Dinno Award in 2023. Among other things, they justified their decision with the innovative automation approach, which they explicitly described as sustainable.
Goodbye control cabinet
So, an award for sustainable mechanical engineering! Behind closed doors, it is said that the jury wanted to send a signal against the continuing wave of control cabinet outsourcing. Whether this is actually the case cannot be proven. The fact is, however, that in recent years, established companies seeking to cut costs have increasingly opted for the cheapest route and had their enclosures installed in countries with lower labor costs. This control cabinet tourism, however, means that thousands of trucks commute between East and West every year.
Many purchasing departments are completely unaware of the disadvantages of this approach. Not only are they willingly giving away their expertise, but they are also losing flexibility. It is very difficult to make changes to the design after the fact.
But that's not all. The award-winning solution focuses on the field level, which has been neglected in most cost-saving programs to date. Yet it is precisely this level that offers machine builders enormous potential for reducing costs and increasing margins. Installation is 40 percent faster than with conventional control cabinet systems, and wiring costs are reduced by as much as 75 percent.
The single-hook machine is no longer just a dream. Murrelektronik makes this possible with its innovative and market-defining solutions.