IO-Link JSON Integration: A Boost for Industry 4.0?

Maxim Babarinow Sep 6, 2020 4 min read
IO-Link JSON Integration: A Boost for Industry 4.0?

The IO-Link community has specified how IO-Link devices and IO-Link masters can be integrated with JSON data models. The definition is fieldbus independent and follows IT concepts with REST, and MQTT. Let us take a look if this specification is a boost for Industry 4.0.

Industry 4.0 and IIoT require transparent and seamless communication from the sensor to higher IT systems. Use cases like condition monitoring or predictive maintenance depend on transparent message formats. Only when this is fulfilled, cost-effective development of new service-oriented business models can be achieved. Plant operators require cross-manufacturer interoperability. They don't want to spend millions on projects, consulting, and training in order to integrate data pipelines with different message formats. This is where the IO-Link and the JSON integration comes in hand.

IO-Link is a standardized technology (IEC 61131–9) which regulates how digital sensors and actuators in industrial systems interact with a controller. The IO-Link community was formed in 2008 and it started the IO-Link consortium with the goal to standardize the hardware (PHY layer) interface and the communication (data) protocol for IO-Link products. There are currently over 300 companies in the consortium including semiconductor vendors and software vendors.

Advantages of IO-Link

Reduced machine cost with an inexpensive standard cable (up to 20 meters) between IO-Link master and IO-Link device. Lower interface diversity and higher interoperability ensure long-term investment protection.

High machine availability in case of a replacement of defective IO-Link devices, the parameters are automatically written to the sensor from the IO-Link master or PLC. Untrained staff can perform the replacement.

Efficient operation of IO-Link devices, which can be attached to the machine, because they don't need to be accessible for parameterization. Parameters can be changed quickly during operation.

Demand-oriented maintenance based on continuous diagnostic data of the complete process can increase maintenance intervals. Automatic parameter adjustments with IO-Link reduce the maintenance effort. Additionally, predictive maintenance is possible.

About IO-Link Market

IO-Link is on the rise, with an annual increase of 40% in 2019 and a total number of more than 16 million installed devices [1,2]. Europe is estimated to have a major share in the global market with 36% according to the Market Reports World. In 2019, the global IO-Link market size was USD 2350.5 million and it is expected to reach USD 5476.8 million by the end of 2026, with a CAGR of 12.7% during 2021–2026.

The consolidated IO-Link world is represented in the IODDfinder ( The parameters of sensors and actuators are defined in the form of IODD (IO Device Description) files which are hosted and distributed through the official repository. The total number of IODD downloads (including all IODD versions and IO-Link revisions) reached nearly half a million in 2019 (Fig. 1), indicating a strong growth rate (Fig. 2).

At the end of 2019, the number of different product IDs (article numbers) referenced in the IODDs reached over 12.000 (Fig. 3). The highest growth rates were reported in the first and second quarter with a maximum of 12% (Fig. 4). The overall numbers show that IO-Link is here to stay.

Fig. 1: Total IODD Downloads (2019)
Fig. 2: Total IODD Downloads Growth in % (2019)
Fig. 3: Product Count (2019)
Fig. 4: Product Count Growth in % (2019)

IO-Link JSON Specification

The JSON Integration for IO-Link has been published in March 2020 [3]. This specification defines a RESTful web service, compact message formats, and MQTT broker communication. In figure 5 we show how the specification can be put to work within an IO-Link gateway.

Fig. 5: High-Level IO-Link Gateway Architecture

The standardized exchange format provides various possibilities for vendors, such as cross-manufacturer engineering tools, global access to measured values, monitoring data, and efficient data pipelining. A cross-manufacturer configuration is possible if the REST API is implemented as a web service. If the gateway is connected with a centralized IoT platform through a cloud gateway even remote configuration and bulk engineering are possible.

Slim sensor to cloud application benefit from using the compact messages which are consumed in an efficient manner when subscribing to the MQTT broker. The compact messaging format reduces cloud data traffic, processing load, and operating costs. The broker resides inside the gateway itself or on a more powerful workstation which can be accessed by multiple gateways within the plant network. Many products can benefit from this specification like: Autosen IO-Key, HARTING MicaLemonage ioFly, or CloudRAIL

This development is going to have a positive impact on IIoT technologies and products by improving interoperability and reducing operational costs for plant operators. We are looking forward to the adoption of the specification by leading IO-Link players like BALLUFFifmWeidmüllerMurrSICKWAGO.





Maxim Babarinow
Founder, CEO
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