The digitalisation of all areas of life is unremitting. Digitalisation promises to further increase the efficiency of production processes and the flexibility of production equipment particularly in the various sectors of industry, through the networking of plants and personnel.

To achieve this, however, the previously rigid hierarchy levels of the automation pyramid must be broken down and standardised interfaces must be created from the sensor to the cloud.

By combining the standardised IO-Link sensor interface and the separate, manufacturer-independent OPC UA communication standard in a single device, Pepperl+Fuchs is creating new ways to make the availability of data end-to-end, transparent, and seamless from the lowest field level up to the cloud.

IO-Link Standardises Sensor Communication

With a total of 11.4 million IO-Link network nodes installed in the field at the beginning of 2019 and a growth rate of around 40 % compared to the previous year, IO-Link has long established itself as a sensor interface in the field and continues to gain in importance.

IO-Link enables standardised data access (IEC 61131-9) to sensors and actuators at the lowest field level.

In contrast to conventional digitally switching or analog sensor technology, IO-Link provides not only access to simple switching signals and data, but also allows access to detailed information, diagnostics, and parameter data for a sensor or actuator.

Smart Sensors are thus enabled with parameter settings that can be automatically adapted to changing production requirements, i.e., during a batch change.

A significant reduction in plant down times is possible with IO-Link. If a problem occurs at field level, the diagnostic data allows for an accurate assessment of the severity of the problem.

If it is necessary to replace devices, the identification data makes it incredibly easy to know which device to obtain from which manufacturer. If the replacement device is installed, all previous parameterisations can be automatically transferred to the replacement device and the plant can switch back to operation, with no need for manual intervention.

OPC UA Enables End-to-End Communication up to the Cloud

While the detailed IO-Link sensor data has so far only been available in the closed control systems on which external data access is scarcely possible, OPC UA opens up new ways to make this data available globally and in a comprehensive manner.

OPC UA is a particularly impressive Ethernet-based communication standard that, due to its independence from manufacturers, programming languages, and platforms, gives customers maximum flexibility in the design of their IoT systems.

OPC UA is significantly different from deterministic fieldbus protocols such as PROFINET or EtherNet/IP, which are familiar from the control world. While these protocols are usually supported only by specialised controllers from the respective manufacturers, OPC UA is ideal for manufacturer-independent communication with a wide range of computer-based or cloud-based systems.

Corresponding OPC UA clients, which create the interface to the OPC UA server, are available for various operating systems and directly integrated with the major cloud providers.

Due to the independence of OPC UA, customers are free to develop their own interfaces. Corresponding supporting development kits are available in this regard from the OPC Foundation. Another difference is the performance alignment of the protocols.

While the control-based communication protocols are primarily geared toward real-time applications with cycle times in the millisecond range, OPC UA is used as more of a parallel, non-time-critical information data channel into the cloud and places less stringent demands on real-time.

Division of Tasks Between PLC and Cloud

Pepperl+Fuchs is the first manufacturer to combine the advantages of IO-Link and OPC UA in a single device. By combining a deterministic fieldbus protocol—such as EtherNet/IP or PROFINET—and OPC UA in a single device, the new IO-Link masters of the ICE2 or ICE3 series can communicate in parallel with a controller and a higher-level PC-based system or cloud.

Hybrid systems are thus possible, in which the PLC controls the application in real-time via PROFINET or EtherNet/IP, and the IO-Link master simultaneously transfers status data to the cloud via OPC UA, that is of no relevance for the controller, but crucial for another machine or a central control system.

Since controllers are specially designed for processing sensor input signals as quickly as possible and transferring the output signals resulting from the control logic back to the actuators as quickly as possible, they are not suitable for large amounts of status data.

They can be processed much more cost-effectively than in computer-based or cloud-based systems, which means expensive computing resources are not required in the controller. By adopting this approach, data can be processed in a local evaluation tool using external software, or uploaded to the cloud without interpretation.

Users can decide if the cloud is located on the corporate network or the internet; they also define the security levels. For this purpose, the IO-Link masters support both authentication mechanisms and certificate management.

Control from the Cloud

The modules from the ICE2 and ICE3 series allow data not only to be read out from the IO-Link devices via OPC UA, but also enable write access if required. For each of the eight ports, it is possible to specify separately for each one whether data should only be read or written via OPC UA.

In principle, applications that do not require control in milliseconds can be implemented in their entirety without a traditional controller. As computer-based and cloud-based systems increase in power and capacity at the same time, control tasks can be assumed at a small cost.

Ready for the Digital Future

With the new IO-Link masters with integrated OPC UA interface, customers are already able to prepare for the digitalisation of their plants. The OPC UA functionality can be enabled and disabled with complete flexibility at any time. This means that customers can already equip their plants accordingly, without a specific application for OPC UA, and unlock the full potential of the ICE2/ICE3 IO-Link masters at any time in the future.

Kgomotso Makhobela
Tel. +27 10 430 0238

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