Catching the right bus! Towards a standard in Digital Communications
One of the most controversial areas in recent years is what has been only half jokingly called the Fieldbus Wars. These are some communications protocols pages that we could find. Where available the English Language pages are listed and where this is not available the language is indicated.
We have not limited our listings to fieldbus communications but have included other types of platform (eg wireless) as well.
We don't pretend that this list is exhaustive and we welcome details of other Communications Web Pages. Please email Readout with details.
The two major protagonists have been identified as International Electrotechnical Commission'sStandard IEC61158 and CENELEC's Standard EN50170. However the latest truce has seen the incorporation of 8 fieldbus standards as the IEC fieldbus standard while the European standard is to add Fieldbus Foundation to its list!
Introduction to Fieldbus The Fieldbus Jungle Fieldbus Can Be Good. Fieldbus Can Be Bad. An Experienced Integrator Examines the Benefits Claimed and Their Relationship to Industrial Reality. (P. Hunter Vegas in ControlDesign 7 Feb 2011)
Moore Industries's useful Introduction to Fieldbus says "Fieldbus is simple. So simple, you'll wonder what all the
fuss is all about. In this article, we'll stick to the two
basic fieldbuses used in process control: PROFIBUS PA
and FOUNDATION fieldbus™ H1. We'll cover how
fieldbus works, show how to connect instruments, and
explain why - in most cases - you can't connect all 32
instruments on a single fieldbus segment as all the
Free, Downloadable White Paper: "Introduction to Fieldbus" - The non-commercial "Introduction to Fieldbus" white paper, downloadable from Moore Industries, explains, in terms any engineer, technician or operator can understand, how fieldbus works. It strips away all the jargon and confusing terminology.
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Fieldbuses for Process Control: Engineering, Operation, and Maintenance by Jonas Berge (2002)
Based on experience collected from end-users in a wide range
of industries around the world, this book provides "how-to"
information for all phases of the system lifecycle from
engineering to device and strategy configuration,
installation, commissioning, troubleshooting, operation, and
The book covers the three leading process fieldbus
technologies: HART, FOUNDATION™ Fieldbus and PROFIBUS-PA.
It covers both the field-level and the Ethernet-based
Bus refers to a concept for cabling devices together, part of a family of connection topologies that also includes the ring and star. The bus topology uses a main trunk cable that connects all devices linearly.
the devices connect to the trunk using drop lines, the bus is called trunk and drop, such as thick Ethernet, Modbus+, AB+, ControlNet, and Proxox DH-II.
If the devices connect directly onto the trunk with no drop lines, the bus is a daisy chain, such as thin Ethernet, Genius I/O, and ProfiBus-DP.
Some buses, such as DeviceNet and Foundation fieldbus H1, can be either.
Ethernet: Thick, thin, or UTP?
Thick Ethernet (10Base-5) was the original IEEE 802.3 Ethernet standard. It is called thick or thicknet because its cable consisted of RG-8U coaxial cable similar to that used for cable TV.
Thin Ethernet (10Base-2) was the second IEEE Ethernet standard. It is often called thin or thinnet because it used the thinner RG-58 A/U coaxial cable at the same data rate.
10Base-T Ethernet, the most common form today, uses unshielded twisted-pair, or UTP, cable in a star topology.
What's the difference?
The terms interoperability and interchangeability are not interchangeable. If two devices can use the same language to talk to a third device, that means they are interoperable with the third device. But if the second device has more bells and whistles than the first, they cannot be interchangeable.
It's like two remote controls that are used on the same TV. They can both talk to the TV, but one has only channel changing and volume capabilities. The other has those capabilities, plus video controls and closed-caption controls. The two remotes are interoperable but not interchangeable.
Bus Web Pages
AS-Interface(ASi) is a cost effective networking solution for the lowest level in the automation hierarchy. This site is to meet market needs and support user group activity in Europe and North America.
ARCNET is a high speed token based network technology used to provide LAN communications between computers in both the industrial and commerical marketplaces.
BACnet - A Data Communication Protocol for Building Automation and Control Networks. BIG-EU represents European interests in the development of the BACnet norm and coordinates European BACnet activities.
CC-Link (Control & Communication Link) is a field network system that processes both control and information data at high speed, to provide efficient, integrated factory and process automation.
ControlNet is another fieldbus standard (Site Location United States of America).
This Measurement Bus was devised as a low-cost interface for the entire range of industrial test and measurement techniques. Information is mostly, though not exclusively in the German language.(Site Location: Germany)
EDDL.org ISA's Electronic Device Description Language (EDDL) standards committee website gives information about the standard and offers resources for learning more about EDDL technology.
HART. The present analogue signal standard in the process industry is 4-20mA. This has been supplemented by HART which allows the transfer of digital data to the device over the analogue wires. Though this is not strictly speaking a true Fieldbus standard is is used in many applications. The Virtual HART Book contains contacts products and sources in addition to technology information.
In March 2000, AG-E, Jetter, Kuka, Lenze, Phoenix Contact and Sick founded The IDA Group to develope a standard Ethernet TCP/IP - based interface for distributed automation solutions.
InterBus-S in German Language (Site Location - Germany) See also the InterBus Club a worldwide organization of users and manufacturers that support the INTERBUS-S industrial I/O bus. (This ite is located in the US but contacts for other parts of the globe are listed. (This has been approved as an international industrial standard by CENELEC as EN 50274.
ISA SP 50 Committee dealing with Signal Compatibility of Electrical Instruments. (Site Location - United States of America). Part 1 and Part 2 of a series about this standard by Richard H. Caro, chairman of the ISA SP50 Committee and chairman of the IEC SC65C/WG6 Fieldbus Committee. (There are a number of interwesting articles now on the web from this source in Intech's Features Section (Scroll down the page untill you come on Fieldbus).
LonWorks (Site Location - United States of America)
MiTS, The Maritime Information Technology Standard is an open communication standard primarily intended for use in integrated ship control systems although it has also found use on land. (Site Location: Norway).
The Mechatrolink Members Association (MMA) mantains Mechatrolink an open fieldbus protocol originally developed by Yaskawa, an industrial network optimised for motion control, and is the most popular motion control network in Asia.
ModBus Protocol has been developed by Modicon (Groupe Schneider). (Site Location - United States of America). See also the Modbus Organisation Inc a non-profit organisation supporting Modbus.
This is the OLCHFA (An Open Low Cost Time-Critical Wireless Fieldbus) Project.
OPC - The OPC Specification is a non-proprietary technical specification that defines a set of standard interfaces based upon Microsoft's OLE/COM technology. The application of the OPC standard interface makes possible interoperability between automation/control applications, field systems/devices and business/office applications. See OPC Foundation for details.
P-NET is based in Denmark. A P-NET site is maintained in English.CENELEC approved
PMBus - The Power Management Bus (PMBus) is an open standard power-management protocol.