A Leap Ahead for IIoT and Cloud Communications

Summary

Data is the heart of digital transformation, the essential enabler of the transition to Industry 4.0 and the industrial internet of things (IIoT). Advanced sensors have been generating and sending data to programmable logic controllers (PLCs) for decades to optimize industrial processes and operations. Now, a new sensor integration gateway based on IO-Link technology can send data to both IIoT/cloud and PLC destinations. It enables digital transformation by providing advanced sensor data processing and communication capabilities at the edge, and it represents a significant leap forward in IO-Link technology.
 

IO-Link and IO-Link Masters

IO-Link is a short-distance, bidirectional, digital, point-to-point, wired (or wireless), industrial communications networking standard (IEC 61131-9) used for connecting digital sensors and actuators to either an industrial fieldbus or to an industrial Ethernet. The technology standard is managed by Profibus and Profinet International.

An IO-Link system consists of an IO-Link master and one or more IO-Link devices, mostly sensors or actuators. The IO-Link master provides the interface to a higher-level controller, typically a programmable logic controller (PLC), to control the communication with the connected IO-Link devices.

The IO-Link communications protocol consists of communication ports, communication modes, data types and transmission speeds. The ports are physically located on the master and provide a means for connecting with terminal devices and bridging to a fieldbus or Ethernet.

In addition to sensor data, IO-Link can also communicate additional production data. All the data types are communicated through an IO-Link master. For example, optical sensors with high-speed digital outputs detect objects (production-side data) while the sensor’s Industry 4.0 side detects how much the laser has degraded in the past three years by recording the intensity of the returning beam. While not critical for production, the latter data set is valuable for reporting on equipment health.
 

The SIG300 Sensor Integration Gateway

The SIG300 Sensor Integration Gateway from SICK is an IO-Link master that bundles and controls sensor communication via eight IO-Link ports (Figure 1). It represents a significant leap forward in IO-Link technology compared to traditional IO-Link masters.

The SIG350: A PLC-centric workhorse

There are important differences between the SIG350 and the SIG300/200.

SICK’s SIG350 sensor integration gateway, which has been on the market for several years, is considered a Level 1 IO-Link master. It conforms to IO-Link specification V1.1.3 to send data to a PLC using Representational State Transfer (REST) and MQTT messaging protocols. It also has very basic logic editing and basic microcontroller capabilities to help with IO-Link master pre-filtering and processing.

The REST software architectural style was created to guide the development of the architecture for the Internet. It emphasizes uniform interfaces, independent deployment of components, the scalability of interactions between them, and creates a layered architecture to promote caching to reduce user-perceived latency, enforce security and encapsulate legacy systems.

The SIG350 is still the go-to if you want only to send raw sensor data to a PLC. As a PLC-centric processor, everything is centralized.

The new SIG300, on the other hand, is a decentralized gateway with the ability to send data to the higher IIoT levels. Its breakthrough technology is the IO device description (IODD) interpreter. Every manufacturer of IO-Link devices must create an XML file that describes exactly what the sensor capabilities are. XML is a markup language and file format for storing, transmitting, and reconstructing data. It defines a set of rules for encoding documents in a format that is both human-readable and machine-readable. This IODD file reveals the location of the memory address for sensor threshold limits of interest.

If you want to get IO-Link data into the PLC, and you like the idea of an IODD interpreter, which cleans the data and parses it for you, SICK has a mechanism called the “function block factory”. This automated digital service creates data parsing within the PLC. You access it through a web form, tell it what your PLC is, what fieldbus you’re using, and what sensor you want to connect to, then it provides a list of every parameter that the IODD file has. You check off the ones you want, and it creates a function block. It sends you a link via email to download the function block, and it gives you all the documentation on how to get that into your PLC

Unique port design and functionality

The SIG300 sensor integration gateway—and its lower-power sibling, the SIG200—comes with the logic editor, which is a user-friendly mechanism to create applications using flow diagrams and/or logic for applications like counting, comparisons, and the like. The SIG300 has eight IO-Link ports accessed through five-pin M12 connectors, which are for the sensors, the digital inputs, and the outputs of the device.

For convenience, the pinout wire diagrams are identified on the front face of the SIG300 (Figure 2). The two Ethernet ports connect the PLC to the MQTT broker or HTTP server. In addition, users can daisy-chain the power via the power-in and power-out connectors (Figure 3).

Benefits of the SIG300 Sensor Integration Gateway

The SIG300 Sensor Integration Gateway from SICK is a powerful and flexible IO-Link master that offers significant advantages over traditional IO-Link masters. Key benefits include:

• An IODD interpreter that automatically parses and formats sensor data, which eliminates the need for manual configuration and parsing on the PLC or server side.
• An integrated logic editor that enables advanced data processing and decision-making directly on the gateway, which reduces the burden on higher-level control systems.
• A dual-talk capability that allows sensor data to be sent simultaneously to the PLC and to cloud/IIoT platforms, which enables parallel data transmission and decentralized processing.
• Configurable to support multiple industrial network protocols (EtherNet/IP, Profinet, EtherCAT) to integrate with existing control systems.

SIG300 applications

The SIG300 has dual-talk capability that allows sensor data to be sent simultaneously to the PLC and cloud/IIoT platforms. This enables parallel data transmission and decentralized processing. It communicates with higher-level control systems like supervisory control and data acquisition (SCADA), REST and MQTT, and provides this functionality through OPC UA.

Parallel data transmission describes the mechanism to send data to multiple different servers. When the sensor and the port are commissioned, each port has the ability to be owned by the PLC, by REST, by the Web user interface (UI), or by the logic editor within the device itself. The concept of “owning” refers to the ability to change something. IO-Link sensors can be accessed and read, but to change something—if I wanted to change a threshold to 90% instead of the default 70%—that’s actually “writing.” I need to own that port to be able to write to it.

The concept of dual talk means that you can read it via REST or in your PLC no matter what. The PLC can configure and make those changes because somebody pushes it on a human-machine interface (HMI), and that HMI threshold goes through the PLC back to the master. Or you can have it coming from REST.

The primary application for a SIG300 is sending data to more than one place. If the user needs only to get IO-Link data into the PLC and wants centralized computing where the PLC controls everything, use the SIG350. The SIG300 is overkill because it has many features that will never be used.
 

Digital transformation: Realized

Sending sensor data to more than one place enables Industry 4.0 and IIoT/cloud applications. By providing advanced sensor data processing and communication capabilities at the edge, the SIG300 sensor integration gateway is a bridge between legacy PLCs and cloud computing architectures. This significant leap forward in IO-Link technology, coupled with smart sensors, enables the digital transformation manufacturers need.