Selecting the right IO-Link hub for industrial automation

When choosing an IO-Link hub for industrial automation applications, there are several factors to consider to ensure it meets your specific requirements.

The following are key aspects to look for:

Check IO-Link version compatibility

Is the hub IO-Link version 1.0 or 1.1? There are features in IO-Link version 1.1 that are not in version 1.0, such as the parameter server and several parameters, like serial number and application tag. If you’re using an older hub or master, make sure each supports the other’s revisions.

Number of I/O ports and port options

Evaluate whether the hub needs to support PNP and NPN inputs. Determine if configurable I/O is necessary at the port or pin level. And assess if a mixture of discrete and analog I/O is needed, and whether dual-density ports are required.

Communication speeds

Historically, typical hubs were commonly operating at COM 2. Due to a growing need to reduce latency, however, many hubs are now being released at COM 3, which represents the fastest speed.

Power

Determine the total current needed by the devices connected to the hub. Verify if the hub can deliver sufficient current through the IO-Link M12 cable, or if it requires an additional auxiliary power connection, such as a 7/8” or L-coded M12 connector, to accommodate the extra current demand. If the hub uses discrete outputs, determine the method for deactivating the outputs through a safety circuit.

Protection

Specify whether the hub should have overall short-circuit protection, where one short circuit protects and powers down the whole unit, or if you need short-circuit protection per port and overload protection per output pin, allowing the other ports to remain operational.

Diagnostics and monitoring

Decide if you need diagnostics, such as short-circuit or overload detection returning to the PLC. Does the hub provide these diagnostics only through event data or through process data? Remember that the larger the data size of the hub, the higher the latency in the minimal cycle time.

Parameterization

Check if the hub operates with its default settings out of the box or if adjustments to some parameter values are necessary. Does the chosen master support ease of parameterization of the hub via a Web UI or parameterization software? Explore whether parameterization can be controlled via REST API, OPC UA, etc.

Mounting and rounding options

Consider the ease of mounting the hub and figure out whether it requires two or four mounting holes and the required bolt size. Does the hub offer a grounding option that meets the grounding requirements of the application? Check if a bounding strip is part of the packaged accessories.

Environmental considerations

Evaluate whether the IP rating fits with the application’s requirements. Does the housing need to withstand exposure to weld slag, cleaning chemicals, or other harsh conditions? What is the required temperature range for the hub? Consider environmental consciousness and identify recyclable components on the hub, if any.

Vendor reputation and support

Consider the availability of local support from the vendor and/or distribution partners. Examine the vendor’s track record and the installed base of these hubs. Explore online information and assess the technical support, including sample code, AOIs, or function blocks.

As IO-Link continues to grow, the number of products and options, even for “simple” IO-Link hubs, can be overwhelming. Make sure to take your time and use these considerations to make a wise choice for your next IO-Link hub.