IO-Link

IO-Link is an I/O connection technology that connects sensors and actuators via simplified wiring and allows them to communicate with programmable logic controllers (PLCs) and human–machine interfaces such as touch panel displays. IO-Link compatible devices, such as sensors and actuators, are connected to an IO-Link master using a single cable to communicate with a PLC collectively, which simplifies data reception and device setting.
IO-Link was released in 2006. It was standardized by the international standard IEC61131-9 in 2013 after PROFIBUS & PROFINET International (PI), which promotes technical standards such as PROFINET, established IO-Link Consortium, a dedicated committee for IO-Link in 2010. Since then, the introduction of IO-Link has accelerated all over the world, especially in advanced facilities in Europe and Asia. Recently, an increasing number of companies have introduced IO-Link in Japan to dramatically reduce the amount of wiring work and improve operation efficiency.

PLC, etc.

Industrial network

IO-Link master

IO-Link compatible devices

Vendors of IO-Link compatible devices, such as sensors and actuators, prepare IO Device Description (IODD) files that contain information such as parameters. IODD files contain information about the manufacturer, model, parameters, and other necessary information. This device information and parameters can be automatically loaded by simply connecting a device to the IO-Link master. Settings can be easily written to connected devices using parameters obtained from IODD files.

A device can be connected to a IO-Link master by simply inserting a single unshielded three- or five-core cable that both supplies power and transmits signals.
M5, M8, and M12 connectors are specified for IO-Link, and M12-round connectors are commonly used for the IO Link masters.

* The connector on the device side may have a different number of pins.

The signal line (C/Q) of IO-Link connectors has two operation modes: IO-Link mode and I/O mode, which handles signals as standard digital I/O signals. The mode can be selected according to the device that is connected.
In IO-Link mode, the following data types can be communicated between the master and devices. Bidirectional communication allows for symptom monitoring, predictive maintenance, and quick troubleshooting.

M12 connectors used for IO-Link have two port classes: class A and class B. The connector pins (pin assignment) of class A and B are used differently. Devices are connected using corresponding connectors.

Conventional wiring work performed on terminal blocks in relay boxes required a lot of time and effort, and presented the risk of incorrect wiring. IO-Link performs both power supply and data transmission by simply connecting a device, such as a sensor or actuator, to the master using a single cable. IO-Link has the following advantages in wiring, connection, and communication.

• A device can be connected using a single cable with no tools, which dramatically reduces the amount of wiring work and risk of incorrect connection. Faulty points are also easily identified.
• Information and parameters of connected devices can be obtained from their IODD files, allowing for quick configuration. Multiple data communication methods are available.
• The cable length can be extended up to 20 m (65.6′), so wiring is highly flexible.
• In IO-Link mode, statuses and problems can be checked at various timing using bidirectional communication between master and devices, which is useful for status monitoring, predictive maintenance, and quick troubleshooting.
• The IO-Link mode has three communication speed standards: COM1, COM2, and COM3. The speed is usually switched automatically according to a connected device, which ensures that the transmission speed required for stable communication is used without any manual configuration. (COM1 = 4.8 kbps, COM2 = 38.4 kbps, COM3 = 230.4 kbps)

Sensor wiring can be completed by simply inserting an M12 connector without using tools. This reduces the wiring work required with conventional relay boxes to approximately one sixtieth. The NQ Series also eliminates the work required to design and create covers and other protective countermeasures because it has a slim, highly durable housing. In addition to simplified wiring, the NQ Series reduces the time required for various wiring work, while saving space on control panels.

Wiring end treatment

Y-shaped terminal processing

Marking tube attachment

Screw tightening

Manufacturer names, device names, and parameters obtained from typical IODD files of connected devices are described in English. This requires users to check with user’s manuals of sensors to identify which setting each parameter corresponds to.
The NQ Series automatically recognizes KEYENCE’s IO-Link compatible sensors when they are connected. Manufacturer names, device names, and parameters obtained from IODD files can also all be localized into Japanese when they are displayed. This saves the time and effort required to verify and check English parameter names, while also preventing incorrect parameter settings caused by misunderstanding.

Settings and parameters for each sensor are backed up with the data storage function of the IO-Link master NQ Series module. For example, when a connected sensor malfunctions, communication can be restored by simply replacing the faulty sensor with a new one. Problems such as temporary stoppage and sensor malfunctions can be identified instantaneously with the master and PLC, and no time or effort are required to set up an alternate sensor, which significantly reduces downtime.

The PC software, NQ Sensor Monitor, is available to download for free to use with the NQ Series. By simply installing it on a PC and connecting the PC to the NQ Series, a variety of operations can be performed easily, including batch setting of multiple sensors, data collection from sensors, output to CSV files, automatic transfer to Excel spreadsheets, and remote monitoring.
Additionally, symptoms can be monitored by managing numeric data collected from connected sensors, which allows for predictive maintenance in which abnormal symptoms are detected early so that action can be taken before problems occur.
The NQ Series can also connect the IO-Link master directly to a PC, without using a PLC, with low latency, which allows use of a PC to monitor devices in real time on site and change device settings remotely.

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