Digital innovations in hydraulic components, such as digitally enhanced high-response directional valves, are moving the needle for machine builders and raising performance standards for machine builders. As hydraulic systems evolve, smart technology is enabling deeper connectivity for more productive machines. IO-Link integration is one advancement that is progressing a machine’s return on investment, the reduction in specialized labor requirements and the improvement of predictive maintenance capabilities to deliver cost-effective, high-performing systems.
Hydraulic IO-Link valves deliver a host of advantages and benefits, including the ability to replace traditional analog controls in open loop and certain closed loop applications where repeatability for consistent results, precision and flexible setup are essential. Common uses include positioning auxiliary functions on presses, transfer operations, lift and position equipment and part ejection.
IO-Link Technology
IO-Link is a form of digital technology that allows communication between a programmable logic controller (PLC) and sensors and switches, or 24VDC actuators like onboard electronic (OBE) valves with an IO-Link interface. This technology has emerged as alternative onboard electronics. It can easily be incorporated into modern OBE circuit designs with minimal effort. In addition to commanding the valve, operators can get actual data like valve output, internal temperature, time in operation, faults and more while modifying valve parameters directly from the machine controller.
Traditional hydraulic control valves may only have a feedback test point for comparison to aid diagnostics. Analog control systems incur higher costs for analog I/O hardware at the PLC end and wiring shielded cables from PLC panel to each valve, which may have long runs which increase exposure to more electrical noise.
IO-Link is implemented through simple, point-to-point connections with pre-made cables to a connection module called the IO-Link master. The IO-Link master connects to a desired field bus and provides 24vdc power distribution to devices. IOLink defines two types of ports: Type A ports for low current sensors and Type B ports with an additional 24V power for valves when typical modules have four to eight ports.
When an IO-Link valve is directly replaced, the IO-Link master automatically loads all parameters to the new component without any manual configuration, allowing for true plug-and-play functionality that can benefit the end user and save time. The required valve electronics adhere to the IO-Link standard, typically featuring a 5-pin M12 connector on the valve for signal conversion to provide power and signal conversion. Each valve is then connected by prefabricated, fixed-length cables — often available in lengths up to 20 meters. These cables then go directly to the bus master, which in turn transfers the communication to the higher level field bus system for integration with the overall control architecture.
Use Cases for IO-Link Valves
Process control and hydraulic machines critical to factory automation operations can be exponentially improved by using IO-Link integrated valves. Precision and flexibility promote efficiency within these machines and ultimately save money and time through maximized productivity.
The latency time in the bus to IO Link Master communication can hinder valve response in a closed loop system. It is better suited for lower dynamic, point-to-point position control. In most cases, cylinders are positioned using SSI position sensors for high resolution on Press equipment, wood processing, as well as plastics and molding machines.
It is advisable to avoid using IO-Link in a closed loop for pressure or force control. Normally, analog feedback sensors are used that are 1 msec or faster which is restricted by the bus master. The valve command with IOLink may work if controlling a very large volume of fluid with low dynamic requirements. Critical applications found on test machines, synchronized axis or interpolated moves are best handled by dedicated motion controllers, integrated fieldbus valves, or integrated axis control valves.
IO-Link is not a one-size-fits-all solution to all functions. For machines pushing the boundaries of performance in the factory automation field with demanding, highspeed functions, motion controllers should still be used due to the demanding axis control and high output. A hybrid approach to valve technology is most likely to yield the best results. In practice, this looks like machine operators utilizing a field bus or analog valve for critical functions, and IO-Link for other axes.
Benefits of IO-Link Valves
While integrated field bus valves have many advantages, these systems are more expensive to install and commission. Each valve requires additional circuitry to accommodate the desired bus interface. Bus connections, large connectors for power and discrete I/O require more space on the valve electrical box. Both OEMs and end users can save money with IOLink integrated valves, despite the higher upfront cost. This trade-off shows when putting required components into motion.
The cost and time savings are key for system builders and installers. Analog has more hardware costs due to the need for added inputs and outputs from the PLC and cabling. With IOLink valves, installation is much faster and there is a reduced need for specialized labor for installation. Installers no longer require in-depth, specialized cabling knowledge and can spend less time finding suitable gauge wire, soldering or crimping wires onto the connectors with loose cables. Instead, five-conductor M12 connector cables are readily available in mass production by cable suppliers.
Machine Building Economics: ROI
End users save time and money from IO-Link integration’s intelligent troubleshooting through the ability to review information about the valves directly from the PLC and HMI interface. In case there are any operating faults, these integrated systems allow for a quick reaction and precise location identification to quickly fix or replace to limit machine downtime. By collecting data and utilizing predictive maintenance on a connected valve, the PLC can monitor any faults or general system performance and make decisions on turning off inputs and outputs. From there, components can be replaced more proactively to save money and time when replacing cables and connectors.
Higher-dollar machine components like pumps with bearings are often a primary focus for replacement, but valves have proven to be critical parts of a machine that need maintenance to maintain optimal system performance. Oftentimes, replacing specific, smaller components can be difficult due to years of wear and tear, so reading the part numbers on the component is essentially impossible due to damage or removal. Digital components with IO-Link integration eliminate this problem with advanced, quick connectivity, making identification and review of part numbers much simpler.
Once PLC programmers configure the IO-Link valve, they can configure switching points, pressure points, flows, ramp times and other parameters for specific components. If valves ever need to be replaced, the IO-Link master can automatically feed these same parameters to the new device. Together, these factors open up new opportunities for faster digital communication and predictive maintenance to ultimately save money in the long term. The convenience of each factor combined cannot be understated in terms of productivity.
The world of industrial automation is evolving rapidly, and more traditional tried-and-true components are catching up to better serve overall operations with the advancement of component connectivity. As plants place greater emphasis on data-driven methods of working, familiar components are being reinvented to meet modern demands. Industrial machines involving lift and position or transfer operations with IOLink valves will continue to advance and become faster over time for improvements in intelligent troubleshooting, predictive maintenance, machine building ROI and ease of installation.
This article was written by Neal Hanson, Industrial Controls Product Manager, Bosch Rexroth (Bethlehem, PA). For more information, visit here .
