In automated machinery and complex industrial systems, pneumatic control management is often one of the most critical elements of the overall system architecture. Fieldbus valve islands are now a well-established solution to this challenge: they combine pneumatic signal distribution and controller communication within a single node, eliminating many of the issues that traditional architectures cannot address effectively.
Why traditional pneumatic architectures show their limitations
In older installations—and still today in many machines designed without a fieldbus integration approach—each solenoid valve is individually wired to the control panel or to the digital output module of the PLC. This approach, apparently straightforward during the design phase, generates a series of complications that become clearly evident during installation, testing and maintenance.
Point-to-point wiring is the first critical element. A machine with 16 or 24 solenoid valves requires an equivalent number of signal cables running through the electrical cabinet, cable ducts and cable glands up to the individual actuators. The practical effect is a crowded control cabinet, long wiring times and a probability of error that increases proportionally to the number of connections. During testing, identifying a polarity reversal or an incorrect connection can take hours.
System complexity is not only a matter of physical space. Valves distributed across multiple points of the machine require equally distributed pneumatic connections, with tubing that multiplies and makes any subsequent modification difficult. Every configuration variant—the addition of a station, a format change or a functional expansion—results in an intervention on the system that affects both the electrical and pneumatic sections.
On the maintenance side, the distributed architecture offers limited visibility. In the absence of integrated diagnostics, a fault in a solenoid valve manifests itself as a functional malfunction of the actuator, without the control system providing any indication of the component responsible. The maintenance technician must proceed by elimination, resulting in longer machine downtime.
Scalability is the most evident limitation during revamping phases. Adding valves to a traditional architecture means adding cables, I/O modules and often modifying the structure of the control cabinet. The designer finds himself working with limited margins, both in terms of physical space and available PLC channels.
What is a Fieldbus Valve Island and how does It work
A valve island is a compact unit that integrates, within a single mechanical assembly, a set of pneumatic solenoid valves, an air distribution manifold and an electronic communication module. Compressed air feeds the manifold at a single point and is distributed internally to the individual valves, eliminating external pneumatic connections between components.
The fieldbus module is the interface node between the valve island and the control system. Instead of individual cables for each solenoid, a single communication cable—or, in the Industrial Ethernet version, an RJ45 connector—connects the valve island to the fieldbus network and the PLC. The module receives commands in the form of telegrams, interprets them and translates them into the activation of the individual solenoids within milliseconds.
From the PLC’s perspective, the valve island appears as a bus node with a unique address. The programmer assigns commands for the individual valves to the corresponding output bits, exactly as would be done with a digital I/O module, but without the need to have that module physically installed in the control cabinet.
Integration with the main programming environments—TIA Portal for Siemens, Studio 5000 for Rockwell and Sysmac Studio for Omron—is achieved through standard GSD, EDS or ESI files, which define the characteristics of the node and enable its automatic configuration.
In addition to output commands, the fieldbus module transmits status data in the opposite direction: supply voltage, internal temperature, communication errors and the status of each solenoid. This bidirectional communication is the key difference compared to traditional wiring, which carries only the command signal without any feedback information.
Benefits of Fieldbus Valve Islands in industrial systems
Reduced Wiring
Wiring savings can be quantified directly. A valve island with 16 valves replaces 16 individual cables with a single communication cable. In a machine with multiple valve islands distributed throughout the layout, the savings multiply. Material and labor costs for wiring are reduced, and the space occupied in cable ducts is freed up for other conductors or simplifies routing within the machine structure.
Modularity and Scalability
Valve islands are designed to grow with the system. Additional valves can be added physically by attaching supplementary modules to the valve island body, without modifying the field wiring. On the software side, reconfiguration of the fieldbus node is limited to updating the configuration file and assigning the new output bits within the PLC program. In a machine project with variants featuring a variable number of stations, this architecture makes it possible to manage different configurations using the same base hardware.
Diagnostics and Monitoring
Real-time diagnostics is one of the aspects that most clearly differentiates fieldbus valve islands from traditional solutions. The communication module continuously transmits information about the status of the valve island: solenoid power supply, short circuit on an individual channel, overtemperature conditions and communication loss. This data is accessible from the PLC and can be managed within the application program to activate alarms, interrupt cycles in a controlled manner or generate maintenance logs. In a plant with SCADA supervision, the same data can be displayed at plant level and stored for predictive analysis.
Simplified Maintenance
The concentration of valves in a single physical location reduces the time required for routine and extraordinary maintenance operations. Replacing a solenoid valve or a module is a localized operation, without the need to trace cables throughout the system. In some configurations, the control module can be replaced without interrupting the valve island power supply, further reducing downtime. Integrated diagnostics guide the maintenance technician directly to the faulty component, eliminating the need for a process of elimination during troubleshooting.
Reduced Installation Time
During machine assembly, the installation and wiring of a preconfigured valve island is significantly faster than installing individual valves. The valve island is tested in the workshop as a stand-alone unit, verifying the functionality of each valve before installation in the field. Commissioning on the production line is reduced to verifying fieldbus communication and testing the PLC program functionality, without the need to inspect individual wiring connections.
Industrial communication protocols and integration in modern systems
The choice of the fieldbus protocol is determined by the automation ecosystem into which the valve island is integrated, and first and foremost by the brand and model of the PLC being used. The main Industrial Ethernet protocols—ProfiNET, EtherCAT and EtherNet/IP—have largely replaced serial buses in new installations, while still coexisting with them in existing production lines.
ProfiNET is the reference protocol within the Siemens ecosystem and is widely used throughout European industry. It supports both cyclic communication for process data and acyclic communication for diagnostics and parameterization. In applications with stringent synchronization requirements, the ProfiNET IRT (Isochronous Real Time) variant provides jitter values below one microsecond.
EtherCAT was developed by Beckhoff and stands out for its extreme real-time performance: communication cycles fall below one millisecond, making it suitable for highly dynamic motion control applications where valve islands must be synchronized with electric axes.
EtherNet/IP, promoted by Rockwell Automation and ODVA, is the dominant protocol in the North American market and in all contexts where Allen-Bradley is the reference standard. It uses the standard TCP/IP stack, which simplifies integration with existing IT infrastructures and communication with MES and SCADA systems.
Profibus DP, although now a mature serial technology, remains present in a large number of existing installations. Valve islands that support this protocol make it possible to integrate new components into Profibus environments without requiring migration of the entire fieldbus network.
IO-Link, finally, is not a fieldbus in the traditional sense of the term, but a standardized point-to-point interface (IEC 61131-9) that enables bidirectional communication between an IO-Link master and a device. In this context, a valve island equipped with an IO-Link module can be connected to an IO-Link master already installed on the system without requiring the availability of an Industrial Ethernet protocol. It is a common solution in medium-sized machines where the number of valves does not justify the introduction of a dedicated bus.
Industrial applications of Fieldbus Valve Islands
Fieldbus valve islands are used in any context where pneumatic automation is combined with a programmable control system. Some industries have adopted them particularly extensively.
- Packaging and packing: automatic secondary and tertiary packaging lines typically use dozens of solenoid valves to control grippers, pushers, cutters, forming plates and vacuum systems. The valve island is mounted directly on the functional unit—closing station, labeling head, filling carousel—reducing tubing to the minimum required and simplifying format changeovers.
- Automated assembly: in assembly systems with multiple stations, each station can be equipped with an independent valve island connected to the machine’s fieldbus network. The designer manages line expansion by adding nodes to the bus without modifying the wiring of existing stations.
- Material handling and handling systems: gripping and transfer systems based on pneumatic cylinders and vacuum cups require a large number of valves operating at high cycle rates. Fieldbus communication enables the PLC to send command sequences with limited latency, compatible with typical production cycles of 200–500 ms.
- Special-purpose machines: in machines built to customer specifications, the modularity of valve islands makes it possible to manage configuration variants using the same mechanical and electrical layout, modifying only the number of installed valve modules and the software configuration of the fieldbus node.
- Automated food and pharmaceutical production lines: in these sectors, where washdown and traceability requirements are stringent, valve islands in IP67 versions or made from materials compliant with industry regulations make it possible to install pneumatic control systems directly in the production area without the need for additional protective enclosures.
Application Example: VJ Series Fieldbus Valve Islands
A concrete example of the application of the principles described above is represented by the VJ Series Fieldbus Valve Islands from Airwork, available in the A&T Fluid Solutions catalogue. The series is available in two main sizes: 10 mm, with flow rates up to 300 l/min, designed for compact machines with reduced energy requirements on both the pneumatic and electrical sides; and 14 mm, with flow rates up to 560 l/min, suitable for larger actuators and more demanding duty cycles.
The modularity of the VJ Series is expressed through the possibility of choosing between four connection modules according to the control architecture: the Sub-D module with a 25-pin connector for traditional wiring installations; the Fieldbus module compatible with ProfiNET, Profibus-DP, EtherCAT, EtherNet/IP and CC-Link IEFB, capable of managing up to 24 solenoid valves, including bistable versions; the Profibus module with 4-pin M12 connections; and the IO-Link module, available in three configurations for 8, 16 and 24 valves, interchangeable with the other modules on the same valve island.
The configuration flexibility allows the designer to choose the protocol according to the PLC ecosystem adopted, without having to change the valve island body or the valves already selected. This reduces the number of part numbers to be managed in multi-customer projects and simplifies spare parts inventory management.
Impact on automation architecture
Fieldbus valve islands represent an evolution of traditional pneumatic architecture, integrating air distribution, control and communication into a single intelligent node. Reduced wiring, integrated diagnostics and greater modularity make it possible to simplify system design, installation and maintenance.
For designers, system integrators and machine builders, adopting these solutions means having a more scalable infrastructure that can be easily integrated with PLCs and supervisory systems, while meeting the requirements of modern industrial automation.
