Industrial Automation

DCU Functionality – Improving Smart Factory Automation

Julian Vosseler

As companies compete to get their products to market faster and cheaper, they need simple solutions to enable near-immediate implementation. However, there’s no time or budget for special tools or expensive, highly-trained engineers and electricians.

In our previous blog on the “4 Benefits of Universal I/O Modules for Smart Factories,” we discussed how universal input/output (I/O) modules allow machine builders to do more with less. Today, we’re discussing how upgrading to a specific type of I/O module – distributed control units (DCUs) – can deliver a new level of efficiency and affordable automation to smart factories.


There’s a growing trend in the automation industry focused on decentralization so machines and production lines operate in a more modular way. This means streamlined operations and maintenance (reducing downtime) and future-proofed factories so new upgrades can easily be configured into the existing network. This change is made possible by the addition of programmable logic controller (PLC) functionality into universal I/O modules via DCUs. A DCU supports separate handling of each part of the production line and acts as a single communication device that connects all components.


What Are DCUs?

DCUs are I/O modules with integrated programmable logic controller (PLC) functionality that connect sensors and actuators. They make automation possible – from simple logical operations to far more complex control problems. Thanks to DCUs, it’s all possible without needing a higher-level PLC, a device that is more difficult to replace in a production line.




Finding an alternative to the PLC is the kind of advancement that’s crucial to manufacturers challenged to constantly improve efficiency. DCUs execute communication, separate diagnostic data from process data and allow cyber-physical connections – all of which alleviate the network traffic burden typically placed on the PLC. This approach keeps operational data from the sensors and actuators close to the affected machine part for easier monitoring of individual machines. And, for security reasons, keeps intellectual property from the sub-systems within the machine itself, a much more secure and decentralized method than passing intellectual property through a PLC.


Universal I/O modules are key to the future of machine builders, especially when integrated with DCU functionality. (pictured)


DCUs give the end user more flexibility than ever before, as they find new ways to improve efficiency, ease of use and installation of technology in their facilities. Here are three modes that a DCU could serve in your network:


Standard I/O Slave
Typically, I/O modules always transmit input data to a controller and will only set an output if the controller tells it to. By operating in standard I/O slave mode, you don’t need a program inside the DCU.


DCU/PLC Mixed Mode
In this type of mode, the intelligence (control program) sits inside the I/O module, but the application only starts and stops, or transmits data to the PLC, on command.


Standalone DCU
The intelligence (control program) sits inside the I/O module, therefore no I/O exchange with the PLC is needed to determine what to do with the signals. It is completely independent from any engineering tool, and connection to the PLC is not necessary. This option brings you to “one-device automation.”


How DCUs Are Addressing Market Trends

When applied in an automated industrial setting, DCUs integrate functional and financial benefits for both the machine builder and end user. Here’s a short list of added DCU benefits that are improving smart factories, driving enterprise innovation and transforming infrastructure.


Smart Factories

Market Trends: Managing big data and cloud computing requires innovative and flexible approaches to link fieldbus machines with IP network technologies. Manufacturers demand intelligent products that allow for faster and easier bus coupling of devices – devices that can share information of any event at any time with the Ethernet network. Easier coupling of devices is paramount when making additions or reconfiguring the parts of a network to reduce downtime.

With DCUs
: DCUs can simplify data transmission solutions and adapt existing systems. This is due to the “plug-and-produce” compatibility that DCUs offer, making them easy to adapt to current systems and to simplify data transmission as it comes from individual machines, rather than being routed to a PLC. (Look for DCUs with multiprotocol options that support the major Ethernet protocols: PROFINET, EtherNet/IP and EtherCat.)


Enterprise Innovation

Market Trends: Companies are under pressure to upgrade their machines so they can take advantage of the newer cloud/Ethernet connectivity solutions and protocols, such as OPC UA. But many older fieldbus machines can’t be monitored via the cloud or Ethernet. With tight budgets, the automation industry has been forced to make a difficult choice: Risk missing out on these advantages or pay the high price to upgrade old units.


With DCUs: DCUs have the ability to make older machines Ethernet-ready, just by placing a DCU directly in the machine and tapping into existing sensor data. This saves the end user the hassle of upgrading with expensive PLCs or gateways, and makes use of their existing machines.


Infrastructure Transformation

Market Trends: The impacts of trends, such as Industrie 4.0, digitalization and globalization on the automation industry have transformed its infrastructure. As more processes are automated, field-level devices can now be installed in harsher environments; environments that may have previously been difficult or hazardous to maintain manually.


With DCUs: DCUs mean fast and easy implementation in smart factories. Module exchange is streamlined by the DCU’s “plug-and-produce” nature. This kind of convenience doesn’t have to be sacrificed when applying DCUs in harsh or remote environments, as some DCUs are rated highly enough to withstand the elements. For example, Belden’s DCU was designed to operate in harsh environments across different sectors, such as automotive or food and beverage manufacturing, material handling or packaging and transportation. It can also be used by machine builders or with robotic machinery.


Because the control program sits inside the I/O module, no I/O exchange with the PLC (like the one shown above) is needed to determine what to do with the signals. This option brings you to “one-device automation.”


How to Start Implementing DCU Applications

More than just fast and easy to install, I/O modules featuring DCUs are designed for immediate implementation. As we reference in Part 1 of this blog, I/O modules follow a “plug-and-play” method. A plug-and-play product, as its name suggests, can simply be connected to an existing machine and turned on. And it works without further configuration.


Buyers just need to remember to spec out a module with as many inputs or outputs as the current module requires. Remember: A true plug-and-play-ready module will come with additional adapters that allow for future changes without the drilling of new mounting holes.


Are you seeing benefits of universal I/Os with your machines? Worried about meeting the challenges of increased global competition? Stay ahead of the curve by downloading Belden’s white paper: "The Road to Plug-and-Produce."