Bruno HÉNON - Automation & Control Engineer Freelance Services in factory automation, designing, programming, installing and subcontracting worldwide

The local area field networks.

Field networks

See also ...


  Automation > Resources > Technologies > Networks > Fieldbuses  

  Ethernet networks in the industry

Fast control dedicated networks  


ArcNet, BitBus, CC-link, CIP, Ethernet IP, Fieldbus, FIP, Modbus, Profibus, Profinet, SafetyBus.

Industrial Networks For General Or For Specialized Usage ?

The word "Fieldbus" has been used for ten of years while industrial networking has been evolving continuously. Consequently, this term has been used (and will be used) in many ways so that it is difficult to understand what does it mean nowadays.

(More generally, which are the notions included in the term "bus" (of data) ? A bus is there a network ? A network is there a bus ? What about using the term "field network" in place of the term "fieldbus" ?)

Which among HART, Modbus, Profibus, IO-Link, Ethernet-IP, Ethercat or Powerlink are or are not fieldbuses for instance ?

This term is there in relation with one specific applications such as process control, motion control, manufacturing automation or machinery automation ?

Is it related to boolean devices only, or to analogical devices only, or to sensors and actuators only ? Does it include the SCADA systems ?

Is a fieldbus based on a specific technology (RS485 or RS232), on a specific architecture (master / slave) or on a specific medium (copper cable for instance) ? An Ethernet sensor network or a wireless device network are they fieldbuses ?

Does a fieldbus depend on its performance ? A 1 Gbps Ethernet field network is there a "fieldbus" ?

What about the term "field level" ? Where does the field begin and where does the field stop ?

An electrical cabinet is there at the field level ? Any data client accessing a fieldbus can be at the field level ? Or only the devices providing data can be at the field level ?

And what about the topology ? Does a fieldbus use a single linear topology only ? Can a network be a fieldbus when using a star topology or a ring topology ?

A definition could be : a "fieldbus" is a network which access directly to the sensors and to the actuators, offering medium performance and rather wide and universal capabilities.

But how acceptable and how pertinent is this definition ?


Specifications and technology, Token technique.

A Widespread Network Technology Without Any Notoriety

"ARCNET" is not a well known technology, despite the fact it is embedded in many industrial fieldbuses and that more than 22 million of nodes have been sold until 2014.

Like Ethernet and Controller Area Network (CAN), ARCNET is a data layer only technology (the application layer is not specified and even not mentioned).

Thus, while developing a new network, the engineers use the Arcnet technology to build the data layer, and they program their own application layer, usually without to mention that the Arcnet technology is embedded in their products.

Consequently, Arcnet is not visible to the user.

The ARCNET networks are structured over bus topology or star topology, using the token technology to manage and to synchronise the data exchanges.

The token technique is particularly convenient for the automation networks, and it is often found in automated applications related to industrial control, robotics and transportation.

ARCNET Specifications And Technical Resources  

The "Arcnet" official site delivers a complete Arcnet introduction, which presents its main features.

You can download there the full specifications of the Arcnet standard and other Arcnet technical resources, including tutorials and libraries.

The Token Ring Technology To Synchronise The Data

The token technique is used for data synchronisation and is a part of many automation fieldbuses architectures such as Arcnet (see above).

This technique is known as token ring, token network and token bus.

The network manager (or the master) puts in circulation a single token which is distributed successively to each connected device.

Once all the devices have transmitted their data, a new tour is initiated (hence the term of "ring").

At a given time, the device which has got the token is the only one authorized device to transmit the data over the network.

Once the transmission has been finished, or whether there are not any data to transmit, the device informs the manager it has finished.

Then, the manager distributes the token to the next device.

This mechanism warrants there will never be any risk of collision during the transmissions.

Features like priority management can be implemented easily and work fine with this technique.

Using the token technology helps to get deterministic behaviour and real time features.



A Master-Slave Field Network

"BITBUS" (IEEE 1118 international standard) is a fieldbus based on widespread and well known technologies such as RS485 serial communications.

It is a simple master / slave network allowing a master to talk with up to 249 slaves.

Specifications, Introduction To The Standard And FAQ

CC-LINK - Control and Communication Link


A Fast And Deterministic Network For The Factory

"CC-link" (Control and Communication Link) is a field network that processes control and information data at high speed with a deterministic behaviour, intended for factory and process automation.

CC-link is a network that was originally developed by the Mitsubishi Electric company, with more than 4 million installed nodes.

The CC-link family consists of CC-link open field network, CC-Link LT (dedicated to sensors and actuators networking), CC-link safety and CC-link IE (1 Gbps Ethernet based fieldbus with two savours : CC-link IE control and CC-link IE-field).

CC-Link Technologies

CIP - Common Industrial Protocol

CIP protocol overview.

An Object Oriented Fieldbus

"CIP" (Common Industrial Protocol) is an object oriented network system which is the base of the end users industrial networks of the CIP family.

Each object has attributes (the data), services (the commands) and behaviour (the reaction to events).

Since CIP-based networks (CIP, ControlNet, DeviceNet, Ethernet IP, CIP safety, CIP motion, CompoNet and many other extensions) are based on a common application layer, the application data remains the same whatever the network.

The application programmer does not even need to know to which network a device is connected.

Features And Introduction To The CIP Protocol  

ODVA is a manufacturer association which supports all the Common Industrial Protocol (CIP) based networks.

The organization manages the development of the technologies and assists the CIP networks users by providing utilities and training support.

ETHERNET IP - A CIP-based Ethernet Network

The official site.

A Field Ethernet Object Oriented Network

"EtherNet/IP", is an Ethernet CIP based network. It is the base of ControlNet too.

Ethernet IP is based on the Session layer of CIP and the other layers above.

The transport layer has been adapted according to the Ethernet standard.

ETHERNET IP Overview And Technical Documentation


Fieldbus Foundation Technology, Technology overview.

A Fieldbus For The Process And The Manufacturing Applications

"Foundation Fieldbus" is a real time open protocol and architecture which has been especially designed to control process and manufacturing applications, with the particularity of communicating directly with instrumentation devices.

It is an all digital communication standard, since it exchanges only digital data, without the need of any 4-20 mA loop, nor any else analogical signal.

In other words, it is a protocol embedded into some instrumentation networks and this "network" basis is called a "fieldbus" (But really, what is a fieldbus ?).

Natively, Foundation Fieldbus uses some widespread standards, such as the Function Block Model, EDDL (Electronic Device Description Language), FDI (Field Device Integration) and FDT.

The main Foundation Fieldbuses versions are "Foundation Fieldbus H1" (initial or original Fiedlbus), "Foundation Fieldbus HSE" (High Speed Ethernet, a Fast Ethernet based network) and "Foundation Fieldbus SIF" (Safety Instrumented Functions)

Fieldbus Technology  

The Fieldbus Foundation organization provides some educational informations on its technologies, with the specifications, tools, training and many more.

Introduction To Fieldbus Foundation And Technical Guides  

Fieldbus incorporated -

FIP - Factory Automation Protocol

WorldFip introduction, Technology basics, Protocol basics.

A Real Time Fieldbus For Control And Instrumentation

"FIP" (Factory instrumentation protocol) has been designed as a real time network entirely digital from a node to another. It allows to connect all the devices of an automated plant (controllers, operator panels, sensors, instrumentation, actuators, inverters etc).

The main characteristic of "WorldFIP" is the usage of a single and simple protocol in order to answer real time communication requirements and to answer background communication requirements for a complete control system or for a complete instrumentation system.

The "FIP" protocol has been created by the "Alstom" company, ant its "WorldFIP" extension has been registered as a European standard with the reference "EN 50170".

Despite the fact that the "WorldFIP" user association has been dissolved in 2007, the CERN in Geneva (Switzerland) has installed more than 450 kms of WorldFIP cables in order to connect about 12 000 nodes, which are controlling parts of the current LHC plant, the "large hadron collider".

Introducing FIP Network  

In its first part, this detailed introduction (29 pages) to "WorldFIP" shows the fundamentals principles, the structure used for communication, the performances and the available topologies.

The second part introduces the "FIP" model and the distributed real time data base (description of the client-server model, of the producer-consumer model etc).

The last part describes the "FIP" structure, according to the OSI layer model.

In this site, hosted by the CERN (Nuclear Research European Centre), you will also find some other informations about the FIP industrial network.

More, you can download an introduction to the FIP protocol ( ).

WorldFIP Technology Overview  

This document of about 25 pages presents the "WorldFIP" technology, beginning with the description of the electronic components and with the description of the communication controller.

Then, you will find a description of the communication libraries, and finally the presentation of some "WorldFIP" dedicated utility software.

Introduction To The WorldFIP Protocol  

This well illustrated tutorial (about 50 pages) describes the physical layer (configuration, speed, coding, frames), the data link layer (addressing, bus arbitration, buffer management) and the application layer (reading, writing, synchronisation).

The next part presents the network management basics, while the last part carries on security and redundancy.


Modbus tutorials, Specifications and technical resources, Modbus Plus.

A Simple, Robust And Popular Automation Network

MODBUS Protocol is a messaging structure developed by Modicon in 1979, used to establish master-slave / producer-consumer communication between intelligent devices.

MODBUS is used to establish a master-slave and provider-customer communication between smart devices.

Modbus Tutorial  

This freelance automation engineer introduces the main features of Modbus protocol.

He compares the properties of Modbus ASCII with the properties of Modbus RTU, then he describes the addressing and the most used requests.

Lammert BIES -

Modbus Specifications And Technical Resources  

This folder provides a set of technical resources in relation with all the different variants of the Modbus networks.

You can get the Modbus specification for all the versions (Modbus RTU, Modbus TCP, Modbus Plus etc) provided by the foundation.

You can access white papers, external links and resources dedicated to modbus, such as Modbus frames analysers, Modbus devices simulators and more.

You will particularly find communication libraries written in various programming languages for many environments (to embed code in your own automation software, a MMI or a PLC application for instance).

Modbus foundation -

Modbus Plus - Planning, Installing And Servicing

Profibus And Profinet Generalities

Profibus, Profinet.

Common Specifications, Technologies, Files, Drivers And Utilities


Profibus official site.

A Widespread Fast And Open Network

"PROFIBUS" is a widespread open communication system often met in factory automation and in process automation.

PROFIBUS is convenient for fast and real-time applications moreover for complex communication usages.

The Profibus family include several versions, related to well defined applications such as Profibus-DP (decentralized peripherals), Profibus-PA (process automation), Profinet (Profibus over Ethernet), Profidrive (motor drives and frequency inverters), Profinet IO and many more.

Specifications, Technology Operating, Technical Forums And FAQ

PROFINET - Profibus Over Ethernet

Profinet official site.

Industrial Ethernet Technology Carrying Profibus

Profinet is quite the universal fieldbus in the Profibus family, since Profinet is a declination of the Profibus system running over Ethernet.

Thus, Profinet benefits of the Ethernet features and of the advantages of industrial Ethernet.

Consequently, Profinet can satisfy all the needs of automation applications, and can be used for factory automation, process control, safety applications and motion control.

Overview Of The Technology, Theory And Practice


Safety bus - The Official Site.

Deterministic And Real Time Ethernet Safety Networks

"SafetyNET p" has been developed as a deterministic real-time Ethernet safe system for industrial environments and applications.

"SafetyNET p" is an evolution of the "SafetyBUS p" safe bus system.

Introduction To The Safetynet Basics  

These short overviews provides informations about the SafetyNET and the SafetyBUS networks, their topology and how they are implemented.

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