Making use of IO-Link in industrial applications
with field devices such as cameras, which can generate many MB of data per minute.
Input devices such as pushbutton switches from RAFI can leverage IO-Link functions to support smart-device features — including color-coded indicator lights.
Conclusion Uses for IO-Link systems abound to complement existing protocols underpinning virtually limitless controls and data-collection systems. Spurring adoption has been the simplicity of IO-Link systems — comprising only an IO-Link primary and its devices and their connectorized three or five-wire cables. Plug-and-play installation and cost-effectiveness are other IO-Link benefits. Efforts by the IO-Link consortium of member companies have ensured wide compatibility between controllers, devices, and actuators from various manufacturers, which has given design engineers the widest selection of equipment for their specific use cases.
sensors that go beyond reporting high or low temperature status by continually reporting the exact temperature value of a monitored zone or volume. Another benefit of IO-Link for smart field devices is the way in which its physical connections are compact. That’s in contrast with the physical connections of fieldbus and Ethernet interfaces, which can sometimes be too big to fit on field microdevices. IO-Link smart components can also be precisely controlled. For example, instead of basic off- and-on controls, an actuator can be commanded to turn off once a scenario satisfies a set of
conditions.
Input devices such as pushbutton switches from RAFI can leverage IO-Link functions to support smart- device features — including color- coded indicator lights. There are some caveats to the use of IO-Link for smart-device applications. Though there is a wireless form of IO-Link under development, it’s still a wired communication protocol — so it is still subject to all the limitations of hard wiring. To maintain data integrity, IO-Link primary-to-device cabling mustn’t exceed 20m. Plus, because the IO-Link protocol can only transmit up to 32 bytes of data per cycle, it’s insufficient for use
Figure 4: An IO-Link system involved in advanced controls includes an IO-Link primary (controller), like the Omron NX-ILM400 shown here, and various IO-Link-enabled sensors, power supplies, and mechatronic devices connected to that primary. IO-Link systems for such applications typically yoke the IO-Link primary and devices to a PLC or other automation system. Image source: Omron
systems having fieldbus and Ethernet-communications
connectivity is that long-distance connections are allowable — which in turn lets installers locate IO-Link primaries in a control cabinet or at the outermost machine reaches if that makes the most sense for a given application. Consider how IO-Link primaries benefit advanced assembly applications by serving as low-level controllers capable of processing both digital and analog signals. Here, primaries might: ■ Accept the data generated by IO- Link linear encoders on the axes of an XY stage ■ Process that data as a gateway ■ Submit that processed IO-Link field-device data to the PLC or other system controller
IO-Link application 3 of 3: device intelligence The third application of IO-Link is to render devices smart. Especially common in sensor designs that resemble legacy sensor options with no (or more modest) programming, these IO-Link-enabled devices can receive instructions, monitor, and execute self-testing routines — and generate data. Because IO-Link also lets devices provide more than basic two-value (yes-no or pass-fail) data, the reporting of precise values is also possible. For example, process-automation tasks benefit from IO-Link temperature
Figure 5: The IO-Link connection interface is very small and can fit on most compact field devices. Shown here is a Balluff BUS004Z proximity sensor with IO-Link connectivity. Image source: Balluff
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