IO-Link

Last updated

IO-Link is a short distance, bi-directional, digital, point-to-point, wired (or wireless), industrial communications networking standard (IEC 61131-9) used for connecting digital sensors and actuators to either a type of industrial fieldbus or a type of industrial Ethernet. [1] Its objective is to provide a technological platform that enables the development and use of sensors and actuators that can produce and consume enriched sets of data that in turn can be used for economically optimizing industrial automated processes and operations. The technology standard is managed by the industry association Profibus and Profinet International.

Contents

System overview

An IO-Link system consists of an IO-Link master and one or more IO-Link devices, i.e. Sensors or Actuators. The IO-Link master provides the interface to the higher-level controller (PLC) and controls the communication with the connected IO-Link devices.

An IO-Link master can have one or more IO-Link ports to which only one device can be connected at a time. This can also be a "hub" which, as a concentrator, enables the connection of classic switching sensors and actuators.

An IO-Link device can be an intelligent sensor, actuator, hub or, due to bidirectional communication, also a mechatronic component, e.g. a gripper or a power supply unit with IO-Link connection. Intelligent with regard to IO-Link means that a device has identification data e.g. a type designation and a serial number or parameter data (e.g. sensitivities, switching delays or characteristic curves) that can be read or written via the IO-Link protocol. This allows parameters to be changed by the PLC during operation, for example. Intelligent also means, however, that it can provide detailed diagnostic information. IO-Link and the data transmitted with it are often used for preventive maintenance and servicing, e.g. it is possible to set an optical sensor in such a way that it reports via IO-Link in good time if it threatens to become dirty. Cleaning no longer comes as a surprise and blocks production; it can now be put on a production break.

The parameters of the sensors and actuators are device- and technology-specific, which is why parameter information in the form of an IODD (IO Device Description) with the description language XML. The IO-Link community provides interfaces to an "IODD Finder", [2] which can be used by engineering or master tools to present the appropriate IODD for a device.

Connector

Cabling is in the form of an unshielded, three or five conductor cables, not longer than twenty meters, and a standardized four or five pin connector. The master and device pin assignment is based on the specifications in IEC 60947-5-2. [3] For a master, two port classes are defined, port class A and port class B. Port class A uses M5, M8, or M12 connectors, with a maximum of four pins. Port class B uses only M12 connectors with 5 pins. M12 connectors are mechanically "A"-coded according to IEC 61076-2-101. [4] Female connectors are assigned to the master and male connectors to the device.

At the master pin 1 to pin 3 provides 24V DC power with max. 200 mA for an optional power supply of the IO-Link device. Pin 4 is used as a digital input (DI) or digital output (DO) according to the IEC 61131-2 specification to allow backward compatibility to proximity sensors according to IEC60947-5-2 or other sensors or electrical switches.

The IO-Link master sends a wake-up current pulse to get the IO-Link device from the serial input-output (SIO) state into the single-drop digital communication interface (SDCI) state. In the SDCI state the IO-Link master exchanges information frames with the IO-Link device.

In a port class A the pins 2 and 5 are not specified and are left to the manufacturer to define. In a port class B the pins 2 and 5 are configured as an additional power supply. [5] [6]

Protocol

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 it a means for connecting with terminal devices and for bridging to a fieldbus or Ethernet. There are four communication modes that can be applied to a port connected to a terminal device: IO-Link, DI, DQ, and Deactivated. IO-Link mode configures the port for bi-directional communications, DI mode configures it as an input, DQ configures it as an output, and Deactivated just simply deactivates the port. There are four data types: process data, value status data, device data, and event data. The protocol can be configured to operate at transmission speeds of either 4.8 kilobaud, 38.4 kilobaud, or 230.4 kilobaud. The minimum transmission time at 230.4 kilobaud is 400 microseconds. An engineering tool is used for configuring the master to operate as the network bridge. [7]

IO-Link Wireless [8] is an extension of IO-Link on the physical level. An IO-Link Wireless Master ("W-Master") behaves like a Master to the superordinate system. There are only virtual ports "down" to the IO-Link Wireless Devices ("W-Devices").

A transmission cycle consists of two phases. To transmit output data, the W master sends a Multicast-W frame (Downlink) with data for the W devices in assigned time slots. Then the W-Master goes on reception and collects in the Uplink Data from the W-Devices which transmit one after the other according to an agreed fixed scheme.

To secure the transmission Frequency Hopping and Channel-Blacklisting are used.

IO-Link Safety [9] is an extension of IO-Link by providing an additional safety communication layer on the existing master and device layers, which thus become the "FS master" and "FS device". One also speaks of the Black Channel principle. The concept has been tested by TÜV SÜD.

IO-Link Safety has also extended the OSSD (Output Switching Signal Device) output switching elements commonly used for functional safety in a non-contact protective device like a light curtain to OSSDe. As with standard IO-Link, an FS-Device can be operated both in switching mode as OSSDe and via functionally safe IO-Link communication.

During implementation, the safety rules of IEC 61508 and/or ISO 13849 must be observed.

Literature

Related Research Articles

<span class="mw-page-title-main">Programmable logic controller</span> Programmable digital computer used to control machinery

A programmable logic controller (PLC) or programmable controller is an industrial computer that has been ruggedized and adapted for the control of manufacturing processes, such as assembly lines, machines, robotic devices, or any activity that requires high reliability, ease of programming, and process fault diagnosis. Dick Morley is considered as the father of PLC as he had invented the first PLC, the Modicon 084, for General Motors in 1968.

<span class="mw-page-title-main">Ethernet over twisted pair</span> Ethernet physical layers using twisted-pair cables

Ethernet over twisted-pair technologies use twisted-pair cables for the physical layer of an Ethernet computer network. They are a subset of all Ethernet physical layers.

<span class="mw-page-title-main">AVR microcontrollers</span> Family of microcontrollers

AVR is a family of microcontrollers developed since 1996 by Atmel, acquired by Microchip Technology in 2016. These are modified Harvard architecture 8-bit RISC single-chip microcontrollers. AVR was one of the first microcontroller families to use on-chip flash memory for program storage, as opposed to one-time programmable ROM, EPROM, or EEPROM used by other microcontrollers at the time.

<span class="mw-page-title-main">KNX</span> Standard in building automation

KNX is an open standard for commercial and residential building automation. KNX devices can manage lighting, blinds and shutters, HVAC, security systems, energy management, audio video, white goods, displays, remote control, etc. KNX evolved from three earlier standards; the European Home Systems Protocol (EHS), BatiBUS, and the European Installation Bus.

A Controller Area Network is a vehicle bus standard designed to allow microcontrollers and devices to communicate with each other's applications without a host computer. It is a message-based protocol, designed originally for multiplex electrical wiring within automobiles to save on copper, but it can also be used in many other contexts. For each device, the data in a frame is transmitted serially but in such a way that if more than one device transmits at the same time, the highest priority device can continue while the others back off. Frames are received by all devices, including by the transmitting device.

The Serial Peripheral Interface (SPI) is a synchronous serial communication interface specification used for short-distance communication, primarily in embedded systems. The interface was developed by Motorola in the mid-1980s and has become a de facto standard. Typical applications include Secure Digital cards and liquid crystal displays.

<span class="mw-page-title-main">Remote terminal unit</span> Computer peripheral to collect telemetry data

A remote terminal unit (RTU) is a microprocessor-controlled electronic device that interfaces objects in the physical world to a distributed control system or SCADA system by transmitting telemetry data to a master system, and by using messages from the master supervisory system to control connected objects. Other terms that may be used for RTU are remote telemetry unit and remote telecontrol unit.

<span class="mw-page-title-main">Profibus</span> Communications protocol

Profibus is a standard for fieldbus communication in automation technology and was first promoted in 1989 by BMBF and then used by Siemens. It should not be confused with the Profinet standard for Industrial Ethernet. Profibus is openly published as type 3 of IEC 61158/61784-1.

<span class="mw-page-title-main">Power over Ethernet</span> System for delivering power along with data over an Ethernet cable

Power over Ethernet, or PoE, describes any of several standards or ad hoc systems that pass electric power along with data on twisted-pair Ethernet cabling. This allows a single cable to provide both a data connection and enough electricity to power devices such as wireless access points (WAPs), Internet Protocol (IP) cameras and voice over Internet Protocol (VoIP) phones.

A fieldbus is a member of a family of industrial digital communication networks used for real-time distributed control. Fieldbus profiles are standardized by the International Electrotechnical Commission (IEC) as IEC 61784/61158.

Actuator Sensor Interface is an industrial networking solution used in PLC, DCS and PC-based automation systems. It is designed for connecting simple field I/O devices in discrete manufacturing and process applications using a single two-conductor cable.

<span class="mw-page-title-main">Profinet</span>

Profinet is an industry technical standard for data communication over Industrial Ethernet, designed for collecting data from, and controlling equipment in industrial systems, with a particular strength in delivering data under tight time constraints. The standard is maintained and supported by Profibus and Profinet International, an umbrella organization headquartered in Karlsruhe, Germany.

IEC 61131 is an IEC standard for programmable controllers. It was first published in 1993; the current (third) edition dates from 2013. It was known as IEC 1131 before the change in numbering system by IEC. The parts of the IEC 61131 standard are prepared and maintained by working group 7, programmable control systems, of subcommittee SC 65B of Technical Committee TC65 of the IEC.

McASP is an acronym for Multichannel Audio Serial Port, a communication peripheral found in Texas Instruments family of digital signal processors (DSPs) and Microcontroller Units (MCUs).
The McASP functions as a general-purpose audio serial port optimized for the needs of multichannel audio applications. Depending on the implementation, the McASP may be useful for time-division multiplexed (TDM) stream, Inter-Integrated Sound (I2S) protocols, and intercomponent digital audio interface transmission (DIT). However, some implementations are limited to supporting just the Inter-Integrated Sound (I2S) protocol.
The McASP consists of transmit and receive sections that may operate synchronized, or completely independently with separate master clocks, bit clocks, and frame syncs, and using different transmit modes with different bit-stream formats. The McASP module also includes up to 16 serializers that can be individually enabled to either transmit or receive. In addition, all of the McASP pins can be configured as general-purpose input/output (GPIO) pins.

Sercos III is the third generation of the Sercos interface, a standardized open digital interface for the communication between industrial controls, motion devices, input/output devices (I/O), and Ethernet nodes, such as PCs. Sercos III applies the hard real-time features of the Sercos interface to Ethernet. It is based upon and conforms to the Ethernet standard. Work began on Sercos III in 2003, with vendors releasing first products supporting it in 2005.

DASH7 Alliance Protocol (D7A) is an open-source wireless sensor and actuator network protocol, which operates in the 433 MHz, 868 MHz and 915 MHz unlicensed ISM band/SRD band. DASH7 provides multi-year battery life, range of up to 2 km, low latency for connecting with moving things, a very small open-source protocol stack, AES 128-bit shared-key encryption support, and data transfer of up to 167 kbit/s. The DASH7 Alliance Protocol is the name of the technology promoted by the non-profit consortium called the DASH7 Alliance.

The Antenna Interface Standards Group is a non-profit international consortium formed by collaboration between communication infrastructure manufacturers and network operators with the purpose of maintaining and developing a standard for digital remote control and monitoring of antenna line devices in the wireless industry. The consortium was established in November 2001 with five original members, and as of March 2019 had 45 worldwide members based in North America, Asia, Europe, and the South Pacific. The consortium has released four versions of its base communication standard, AISG v1.0,AISG v1.1,AISG v2.0and AISG v3.0. The consortium has also released stand alone standards that specify details related to its base standard. These standards include a standard for the connector used in AISG RS-485 based bus, standard for RF connector markings on the antenna faceplate and standards for distributing software and configuration files wrapped in XML. All published AISG standards can be downloaded from the AISG webpage.

The IODD describes sensors and actuators with an IO-Link communication interface. It contains information about the device’s identity, parameters, process data, diagnosis data, communication properties and the design of the user interface of engineering tools. The IODD comprises different data files: the main file and several optional language files are in XML-format and optional graphical files are in PNG-format.

<span class="mw-page-title-main">USB-C</span> 24-pin USB connector system

USB-C is a 24-pin USB connector system with a rotationally symmetrical connector. The designation C refers only to the connector's physical configuration or form factor and should not be confused with the connector's specific capabilities, which are designated by its transfer specifications. A notable feature of the USB-C connector is its rotational symmetry; a plug may be inserted into a receptacle in either orientation.

<span class="mw-page-title-main">IEC metric screw sized connectors</span>

IEC metric screw sized connectors is a family of electrical connectors defined by IEC that are named according to their ISO metric screw thread, namely M5, M8 and M12. The number gives their outer screw thread diameter in millimeters as with the identically named screws. However, the connectors are further classified by a so-called coding, denoted by one or more letters, which defines things like pin layout, shape of connecting surfaces and electrical properties.

References

  1. ↑ "IO-Link System Description – Technology and Application" (PDF). IO-Link Company Community. 2018. Retrieved 2020-05-19.
  2. ↑ "IODD finder". IO-Link Community Consortium. Retrieved 27 September 2018.
  3. ↑ "IEC 60947: Low-voltage switchgear and controlgear - Part 5-2: Control circuitdevices and switching elements - Proximity switches". International Electrotechnical Commission. Retrieved 2020-05-19.
  4. ↑ "IEC 61076-2-101: Connectors for electronic equipment - Product requirements - Part 2-101: Circular connectors - Detail specification for M12 connectors with screw-locking". International Electrotechnical Commission. Retrieved 20 June 2018.
  5. ↑ "IO-Link Interface and System Specification" (PDF). IO-Link Community Consortium. Retrieved 20 June 2018.
  6. ↑ "IO-Link System Description" (PDF). IO-Link Community. Retrieved 20 March 2023.
  7. ↑ "What is IO-Link?". IO-Link Consortium Community. Retrieved 12 June 2018.
  8. ↑ "IO-Link Wireless Exposé" (PDF). IO-Link Consortium Community. Retrieved 27 September 2018.
  9. ↑ "IO-Link Safety System Description, Technology and Application" (PDF). IO-Link Consortium Community. Retrieved 10 October 2018.

Io-Link Communication Io-Link Io-Link Sensors

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.