Fieldbus & Industrial Networking

IO-Link eases sensor connection

April 2022 Fieldbus & Industrial Networking

Most process plants have auxiliary services that do not require sophisticated instrumentation; more basic sensors are adequate, while also being more cost-effective.

IO-Link offers an easy way to integrate these devices. It comprises IO-Link masters (comparable to a remote I/O), each with IO-Link devices, which can be sensors or actuators, connected via standard three-core cables. It is typically a subsystem of a larger, plant-wide monitoring and control network.

IO-Link master-device communication uses a digital point-to-point UART protocol rather than fieldbus networking. This manages the transfer of parameters to devices and collection of diagnostic and measurement information from them. The IO-Link master exchanges data with higher levels through Profinet, Ethernet/IP and many other protocols.

As an industrial communications networking standard, IO-Link’s devices, while more basic, still offer the data-rich visibility and controllability benefits of digital technology. The standard that applies to IO-Link, defined as IEC 61131-9, has now evolved from version 1.0 to version 1.1.

What challenges does IO-Link address?

For traditional systems, the loading of parameters for system and machine commissioning has always been a costly and time-consuming factor. Time and expense can similarly be wasted reloading parameters after instruments have been swapped out – and this parameterisation must be performed online, causing further production delays.

This is also a problem in a system manufacturing environment. Time is lost as the same parameters are entered into each unit of a system production batch.

Once in operation, such systems can be prone to failure and downtime as sensors do not provide status data to help spot latent problems. Even without a significant system failure, identifying and diagnosing problems in traditional instruments can be difficult and time-consuming and may require the expertise of a skilled technician to resolve.

Logistics complexity and delays can also arise, as well as onerous stocking costs, if a process needs multiple devices with varying configurations. Often, differences between sensors can be small, for example 0 to 10 bar versus 0 to 100 bar. Nevertheless, this represents a difference in parameterisation which may have to be performed by the instrument vendor. This is exacerbated if each device type calls for its own cable and/or connector, possibly of elevated specification.

IO-Link is a solution that can be used anywhere except in hazardous areas. It offers solutions to these issues through its communications capabilities. In a standardised environment, each sensor has a unique identification comprising a vendor ID and a device ID. It can continuously deliver data packets that include 32 bytes of process data, a status bit, parameter and diagnostic device data and event data such as error messages.

Planning and parameterisation of an IO-Link system can be performed using I/O Device Description (IODD) and an engineering tool. This allows easy device configuration, while stockholding for different device types is reduced. Parameterisation can be performed remotely, offline or online, using the engineering environment of the automation system. Complexity on the factory floor is also reduced, as all IO-Link device types connect to their IO-Link masters via standard 3- or 5-core unshielded cables and use industry-standard M12 connection plugs. Cables can be up to 20 metres in length.

Once the system becomes operational, maintenance, repair and operation (MRO) is accelerated. New repair and maintenance concepts become possible through IO-Link’s self-diagnosis and self-parameterisation capabilities, with value added to process measurements by detailed status and error data. Sensors often provide other values, such as temperature, alongside the main measurement, or continuous measurement values alongside a switch status.

IO-Link functions as a compelling alternative to simply monitoring non-digitalised devices such as 4-20 mA transmitters or digital input switches, which permit only one process variable per cable pair. Such devices also require scaling and local configuration – operations that must be repeated manually every time a device is exchanged.

How does IO-Link benefit users?

IO-Link offers easy and efficient integration through the use of standardised function blocks. It also complements Industrial Ethernet well, since high-end Ethernet devices can operate alongside more basic IO-Link sensors and actuators.

A traditional control system’s wide variety of sensors would have many different analog and digital signal types – digital in (DI), digital out (DO), PNP, NPN, pulse, 0-10 V, 4-20mA and possibly others. These would all generate requirements for their own connector and cable types. By contrast, all IO-Link devices use a common standard cable, which reduces inventory stock-holding, complexity and installation time. Once installation is complete, commissioning and start-up are accelerated by the automated setting of parameters.

If problems occur, the system provides diagnostic information with cause and remedy; this includes cable break detection. If diagnostics indicate that a device needs changing, this can be facilitated through automatable parameter data storage and download.


Share this article:
Share via emailShare via LinkedInPrint this page

Further reading:

Intrinsically safe EtherCAT I/O modules
Beckhoff Automation Fieldbus & Industrial Networking
As a robust alternative to IP20 solutions with their elaborate housing protections, EPX modules with IP67 protection rating enable reliable data collection.

How utility instrumentation can benefit your plant
Endress+Hauser South Africa Analytical Instrumentation & Environmental Monitoring
An auxiliary plant instrument reading has to be available on demand, otherwise potentially serious problems may remain hidden.

Modbus probes gain support for parity options
RF Design Fieldbus & Industrial Networking
The marquee feature of firmware version 1.06 facilitates the use of odd, even, mark or space parity modes when communicating with bus probes.

Compact and powerful energy monitoring unit
Opto Africa Holdings Electrical Power & Protection Fieldbus & Industrial Networking
The RIO EMU’s slim form factor is ideal for ‘just one more thing’ retrofit jobs thanks to DIN-rail and panel-mount options.

Is your manufacturing plant ready for IoT?
Editor's Choice Fieldbus & Industrial Networking IT in Manufacturing
Pockets of IoT exist in manufacturing plants today; the challenge is to fully digitalise the entire plant.

Extend the life of your legacy devices
RJ Connect Fieldbus & Industrial Networking
If your serial-based machines or devices have been running for decades and helped your business grow, you might worry about how long you can still hold on to these assets. In this article, we highlight three major challenges you will face when enabling serial connectivity between your legacy devices and modern systems. We also provide expert tips to make your upgrade easy.

Water and wastewater treatment in the digital age
Endress+Hauser South Africa Editor's Choice Analytical Instrumentation & Environmental Monitoring
In these testing times of declining water security, IoT technology has been proven to boost operational efficiency and inform smart investment decisions.

AS-i and IO-Link power distributor for hygienic areas
Fieldbus & Industrial Networking
The special housing material and high ingress protection allow operation in areas with frequent intensive cleaning processes, for example in the food industry.

Upgraded IIoT functionality for excom Ethernet I/O
Turck Banner Fieldbus & Industrial Networking
Firmware update adds functions to excom Ethernet gateways, such as webserver, HCiR and parallel access to HART devices.

IO-Link master with OPC UA interface
Pepperl+Fuchs Fieldbus & Industrial Networking
The combination makes data accessible beyond the central control system, for decision-makers to access without complex workarounds.