DeviceNet

Last updated

DeviceNet is a network protocol used in the automation industry to interconnect control devices for data exchange. It utilizes the Common Industrial Protocol over a Controller Area Network media layer and defines an application layer to cover a range of device profiles. Typical applications include information exchange, safety devices, and large I/O control networks. [1]

Contents

History

DeviceNet was originally developed by American company Allen-Bradley (now owned by Rockwell Automation). It is an application layer protocol on top of the CAN (Controller Area Network) technology, developed by Bosch. [2] DeviceNet adapts the technology from the Common Industrial Protocol and takes advantage of CAN, making it low-cost and robust compared to the traditional RS-485 based protocols. [3]

In order to promote the use of DeviceNet worldwide, Rockwell Automation has adopted the "open" concept and decided to share the technology to third-party vendors. Hence it is now managed by ODVA, an independent organization located in North America. ODVA maintains specifications of DeviceNet and oversees advances to DeviceNet. In addition, ODVA ensures compliance to DeviceNet standards by providing conformance testing and vendor conformity.

ODVA later decided to bring DeviceNet back to its predecessor's umbrella and collectively refer to the technology as the Common Industrial Protocol or CIP, which includes the following technologies:

ODVA claims high integrity between the three technologies due to the common protocol adaptation, which makes industrial controls much simpler compared to other technologies.

DeviceNet has been standardized as IEC 62026-3. [4]

Architecture

Technical Overview Define the OSI seven-layer architecture model the physical layer, data link layer and application layer

  1. Network in addition to the signal, but also including power, self-powered support network function (generally used in small devices, such as photo detectors, limit switches or proximity switches, etc.) [2]
  2. Allows three bit rates: 125 kbit/s, 250 kbit/s and 500 kbit/s, the main trunk under different bit rates (trunk) is inversely proportional to the length and bitrate
  3. Flat cable network can be used
  4. Single network can have up to 64 nodes, node address (called MAC ID in DeviceNet) by 0–63. Usually the default address for a new out of the box device is 63
  5. Duplicate node address detection function
  6. Supports master-slave and end-to-end (peer-to-peer) communication architecture, but most of the equipment is operating in the former network architecture
  7. Multiple network allows a single master function
  8. Can be used in high-noise environments

Physical layer

Nodes are distributed along a DeviceNet network by the means of a trunkline-dropline topology. This topology allows for ease in wiring and access to the network from multiple taps. In addition, nodes can be easily removed and added to reduce production downtime, increase network flexibility, and decrease troubleshooting time. Since the physical layer is optically isolated from the device, communication power and device power can share the same bus (further reducing the complexity of the network and components within). (Introduction [5] )

DeviceNet supports 125 kbit/s, 250 kbit/s and 500 kbit/s data rates. Depending on the chosen cable type, DeviceNet can support communication up to 500 meters (using round, large diameter cable). Typical round cable supports up to 100 meters, while flat-style cable supports up to 380 meters at 125 kbit/s and 75 meters at 500 kbit/s. (Physical Layer [5] )

DeviceNet uses a differential serial bus (Controller Area Network) as its Data Link Layer. Using CAN as a backbone, DeviceNet requires minimal bandwidth to transmit and package messages. In addition, a smaller processor may be selected in the design of the device thanks to the data frame format and the ease at which the processor can parse the data. See below for full format. (The Data Link Layer [5] )

CAN Data Frame Format

1 bit      => Start of frame 11 bits    => Identifier 1 bit      => RTR bit 6 bits     => Control field 0–8 bytes  => Data field 15 bits    => CRC sequence 1 bit      => CRC delimiter 1 bit      => Acknowledge 1 bit      => Ack delimiter 7 bits     => End of frame >2 bits    => Interframe space

Reference: Table: Data Frame Format. [5]

Upon transmitting the first packet of data, the Start of Frame bit is sent to synchronize all receivers on the network. The CAN identifier (denoted from 0–63) and RTR bit combine to set priority, at which the data can be accessed or changed. Lower identifiers have priority over higher identifiers. In addition to transmitting this data to other devices, the device also monitors the data sent. This redundancy validates the data transmitted and eliminates simultaneous transmissions. If a node is transmitting at the same time as another node, the node with the lower 11 bit identifier will continue to transmit while the device with the higher 11 bit identifier will stop. (Introduction & Physical Layer. [5] )

The next six bits contain information for specifying the Control Field. The initial two bits are fixed, while the last four are used to specify length field of the Data Field. The Data Field contains from zero to eight bytes of usable data. (Physical Layer. [5] )

The following data frame is the CRC field. The frame consists of 15 bits to detect frame errors and maintains numerous format delimiters. Due to ease of implementation and immunity to most noisy networks, CAN provides a high level of error checking and fault confinement. (Physical Layer. [5] )

Network

DeviceNet incorporates a connection-based network. A connection must initially be established by either an UCMM (Unconnected Message Manager) or a Group 2 Unconnected Port. From there, Explicit and Implicit messages can be sent and received. [6] Explicit messages are packets of data that generally require a response from another device. Typical messages are configurations or non-time sensitive data collection. Implicit messages are packets of data that are time-critical and generally communicate real-time data over the network. An Explicit Message Connection has to be used to established first before an Implicit Message Connection is made. Once the connection is made, the CAN identifier routes data to the corresponding node. (The Network and Transport Layers. [5] )

See also

Notes

  1. ↑ Archived 2015-09-24 at the Wayback Machine , DeviceNet Technology Overview.
  2. ↑ Controller Area Network Solutions FAQ (Frequently Asked Questions), What is DeviceNet?
  3. ↑ "Eurotherm Parker SSD Link Hardware L5351 | Automation Industrial". l5351.com. Retrieved 2024-01-12.
  4. ↑ "IEC 62026-3:2014: Low-voltage switchgear and controlgear - Controller-device interfaces (CDIs) - Part 3: DeviceNet". IEC. Retrieved 20 July 2016.
  5. 1 2 3 4 5 6 7 8 "DeviceNet Technical Overview" Archived 2007-01-28 at the Wayback Machine from Open DeviceNet Vendor Association, Inc. (ODVA)
  6. ↑ Odva, DeviceNet (2021). "CIP on CAN Technology" (PDF). Technology overview series.

Related Research Articles

<span class="mw-page-title-main">OSI model</span> Model of communication of seven abstraction layers

The Open Systems Interconnection model is a conceptual model from the International Organization for Standardization (ISO) that "provides a common basis for the coordination of standards development for the purpose of systems interconnection." In the OSI reference model, the communications between systems are split into seven different abstraction layers: Physical, Data Link, Network, Transport, Session, Presentation, and Application.

<span class="mw-page-title-main">Network topology</span> Arrangement of the elements of a communication network

Network topology is the arrangement of the elements of a communication network. Network topology can be used to define or describe the arrangement of various types of telecommunication networks, including command and control radio networks, industrial fieldbusses and computer networks.

<span class="mw-page-title-main">I²C</span> Serial communication bus

I2C (Inter-Integrated Circuit; pronounced as “eye-squared-C”), alternatively known as I2C or IIC, is a synchronous, multi-master/multi-slave (controller/target), single-ended, serial communication bus invented in 1982 by Philips Semiconductors. It is widely used for attaching lower-speed peripheral ICs to processors and microcontrollers in short-distance, intra-board communication.

<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.

Zigbee is an IEEE 802.15.4-based specification for a suite of high-level communication protocols used to create personal area networks with small, low-power digital radios, such as for home automation, medical device data collection, and other low-power low-bandwidth needs, designed for small scale projects which need wireless connection. Hence, Zigbee is a low-power, low-data-rate, and close proximity wireless ad hoc network.

A controller area network is a vehicle bus standard designed to allow microcontrollers and devices to communicate with each other. 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.

<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.

LonWorks or Local Operating Network is an open standard for networking platforms specifically created to address the needs of control applications. The platform is built on a protocol created by Echelon Corporation for networking devices over media such as twisted pair, power lines, fiber optics, and wireless. It is used for the automation of various functions within buildings such as lighting and HVAC; see building automation.

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.

<span class="mw-page-title-main">Industrial Ethernet</span> Use of Ethernet in an industrial environment

Industrial Ethernet (IE) is the use of Ethernet in an industrial environment with protocols that provide determinism and real-time control. Protocols for industrial Ethernet include EtherCAT, EtherNet/IP, PROFINET, POWERLINK, SERCOS III, CC-Link IE, and Modbus TCP. Many industrial Ethernet protocols use a modified media access control (MAC) layer to provide low latency and determinism. Some microprocessors provide industrial Ethernet support.

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> Computer network protocol

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.

Ethernet Powerlink is a real-time protocol for standard Ethernet. It is an open protocol managed by the Ethernet POWERLINK Standardization Group (EPSG). It was introduced by Austrian automation company B&R in 2001.

CANopen is a communication protocol and device profile specification for embedded systems used in automation. In terms of the OSI model, CANopen implements the layers above and including the network layer. The CANopen standard consists of an addressing scheme, several small communication protocols and an application layer defined by a device profile. The communication protocols have support for network management, device monitoring and communication between nodes, including a simple transport layer for message segmentation/desegmentation. The lower level protocol implementing the data link and physical layers is usually Controller Area Network (CAN), although devices using some other means of communication can also implement the CANopen device profile.

EtherCAT is an Ethernet-based fieldbus system developed by Beckhoff Automation. The protocol is standardized in IEC 61158 and is suitable for both hard and soft real-time computing requirements in automation technology.

EtherNet/IP is an industrial network protocol that adapts the Common Industrial Protocol (CIP) to standard Ethernet. EtherNet/IP is one of the leading industrial protocols in the United States and is widely used in a range of industries including factory, hybrid and process. The EtherNet/IP and CIP technologies are managed by ODVA, Inc., a global trade and standards development organization founded in 1995 with over 300 corporate members.

ControlNet is an open industrial network protocol for industrial automation applications, also known as a fieldbus. ControlNet was earlier supported by ControlNet International, but in 2008 support and management of ControlNet was transferred to ODVA, which now manages all protocols in the Common Industrial Protocol family.

Profisafe is a standard for a communication protocol for the transmission of safety-relevant data in automation applications with functional safety. This standard was developed jointly by several automation device manufacturers in order to be able to meet the requirements of the legislator and the IFA for safe systems. The required safe function of the protocol has been tested and confirmed by TÜV Süd. The PROFIBUS Nutzerorganisation e.V. in Karlsruhe supervises the standardization for the partner companies and organizes the promotion of this common interface.

Generic Substation Events (GSE) is a control model defined as per IEC 61850 which provides a fast and reliable mechanism of transferring event data over entire electrical substation networks. When implemented, this model ensures the same event message is received by multiple physical devices using multicast or broadcast services. The GSE control model is further subdivided into GOOSE and GSSE.

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.

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.