Talk:Fieldbus
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[edit] Rewrite
The Article used to describe specifically the FOUNDATION fieldbus. I did the following:
- Incorporated the information from fieldbus control systems
- Requested fieldbus control systems for deletion
- Wrote an introduction
- Added some standards.
- Moved the Information that was peviously here to FOUNDATION fieldbus
--BjKa 08:55, 25 August 2005 (UTC)
The complete article is outdated. Is it possible to have an expert refresh it?
I agree fully. The article is to say the least outdated. The german wiki artikle de:Feldbus is significantly better and could be a good base if translated. I'm even willing to translate it, but replacing the whole article is something I'm hesitant as I'm relatively new at the en-wiki --Kramer-Wolf 09:33, 26 February 2007 (UTC)
I have changed the formating a bit to look more formal and moved some of the sections around. I'm willing to help out with the structure if Kramer-Wolf translates the page from German. The page could be updated section by section. By adding a 1 new section at a time. Existance is a struggle between life and death. I just like to watch. 17:15, 1 August 2007 (UTC)
[edit] Field bus
Isn't the generic term really "field bus" rather than "fieldbus"? Also, this page seems to be describing just one instance of the generic concept of a field bus. The Controller Area Network bus would be another example of a field bus. Unfortunately, I'm not an expert.
Correct -> it should read field bus Kramer-Wolf 09:26, 26 February 2007 (UTC)
Made a significant number of edits relating to current position (2007)
[edit] Different?
What is the unique difference between field bus technology and regular buses and computer networks? --Abdull 14:13, 11 March 2007 (UTC)
With field busses, the environmental part is far more a focus, while the physics of communication is often "old fashioned". There are often precise specs about wiring, connectors, network structures, diagnostics, automated tests for the devices, protection levels. Remember: The field busses were the first multi vendor communication systems, even though there (still) is typically one big player with each of the systems. That's one of the reasons why there are so many of them. Kramer-Wolf 08:31, 14 March 2007 (UTC)
[edit] Disadvantages - noise
I was under the impression that in general, digital signals are less susceptible to noise than analog, because any amount of noise will affect the transmitted analog signal, whereas digital signals are only affected if the magnitude of the noise is comparable to the quantization level of the signals. Why would this be different for field bus? 192.75.48.150 20:51, 30 April 2007 (UTC)
To my experience and theoretical background as well you are quite right. Some explanation never the less: In some applications it does not matter to have a temporarily wrong analogue value, while a detected wrong digital value causing a communication break down is unacceptable. So especially systems with slow cylce rates (seconds or so) and high availability requirements still favour analogue systems in some respect. All others certainly live much better with digital communication and error detection/correction mechanisms. Kramer-Wolf 07:28, 2 May 2007 (UTC)
The difference in this case is that the signal that is used is not a voltage signal, but instead is a current signal. It is much more difficult to affect a current signal, since the magnetic field, that typically greatly affects a voltage signal, generally does not have enough power to affect the current signal for a significant amount of time. --Existance is a struggle between life and death. I just like to watch. 17:20, 1 August 2007 (UTC)
[edit] Device power on Ethernet claim ?
In the article: "Currently the issue stopping most Ethernet fieldbus implementations is the availability of device power. Most industrial measurement & control devices need to be powered from the bus and Power-Over-Ethernet (PoE) does not deliver enough."
First of all, most of the traditional fieldbusses do NOT supply bus power. Only DeviceNet and ASI, and perhaps one more fieldbus can supply bus power. The highly popular profibus does not. So I do not agree that the availability of bus power is what is limiting Ethernet acceptance. Secondly, Power over Ethernet can deliver 13 Watts of power. This is more than enough for any bus powered field device. So even the second claim that PoE does not deliver enough is simply false.
I would say that Ethernet acceptance is more likely limited by the higher higher prices, the impractical star-structure of Ethernet networks, limited availability of field devices with Ethernet support (Profinet IRT, EtherCAT, Powerlink), questionable determinism (Ethernet/IP, Modbus, Profinet IO), questionable reliability under harsch conditions (RJ45 is certainly not the most rugged connector on the market, and rugged alternatives are typically not standardised).
Did you know that the modern 100Mbit Ethernet/IP and Profinet IO protocols are actually slower than their old 5Mbit/12Mbit predecessors, ControlNet and Profibus? Brolin 00:48, 7 July 2007 (UTC)
