XML Support, Knowledge & FAQ

 

Data Sheets and Manuals

 – Data Sheet – FieldServer Driver – Ethernet – FS-8704-15 – XML

Data Sheet – FieldServer Driver – Serial – FS-8704-15 – XML White Paper

Manual – FieldServer Driver – Serial – FS-8704-15 – XML White Paper

Data Sheet – FieldServer Driver – Serial – FS-8704-01 – SMC TCP/IP

Manual – FieldServer Driver – Serial – FS-8704-01 – SMC TCP/IP

Data Sheet – FieldServer Driver – Ethernet – FS-8704-03 – Modbus TCP

Manual – FieldServer Driver – Ethernet – FS-8704-03 – Modbus TCP

Manual – FieldServer Driver – FS-8704-03 – Convia XML

Data Sheet – FieldServer Driver – FS-8704-03 – Convia XML

Data Sheet – FieldServer Driver – Serial – FS-8705-14 – Harshaw Trane – Driver for XML HVAC Building Automation Schedules

More Data Sheets

FieldServer White Paper

XML as an Industrial Data Communications Protocol

 

Abstract

With the ubiquity of high speed data networks (10, 100 and 1000 Mbits/sec) the bandwidth ‘cost’ of transferring bloated English text based data messages has become minimal. XML is a meta Language – a language for describing other languages. SGML is the Standard Generalized Markup Language the international standard for defining descriptions of the structure of different types of electronic document. XML is a subset of SGML. As such it is perfect for defining a data communications protocol where the queries, responses and data are self describing and self documenting. A protocol whose messages do not require a reader to have access to the protocol specification to make sense of them but which still complies with a standard in terms of formatting and parsability has been a popular goal. This paper outlines a method for achieving this.

 

XML – A Short Primer

XML is an acronym for “Extensible Markup Language”, it is a project of the World Wide Web Consortium (W3C), and the development of the specification is being supervised by their XML Working Group. A Special Interest Group of co-opted contributors and experts from various fields contributed comments and reviews by email. XML is a public format: it is not a proprietary development of any company. The v1.0 specification was accepted by the W3C as Recommendation on Feb 10, 1998.

XML was developed for the internet as a replacement for HTML. Thus, its is a markup specification language with which you can design ways of describing information (text or data), usually for storage, transmission, or processing by a program: it says nothing about what you should do with the data (although your choice of element names may hint at what they are for):

As a meta language you must understand that the XML elements do not in themselves describe information or information transmission but the XML elements can be used to define one or more structures of information or information transmissions.

Thus one person may use XML to define a conversation as follows

 

<conversation>
<greeting>Hello, world!</greeting>

<response>Hi!</response>
</conversation>

 

And another person may use the following structure.

 

<conversation>
<greeting>
<spoken_by>Speaker1</spoken_by>
<tone>normal></tone>
<spoken_text>Hello!</spoken_text>
</greeting>
<response>
<spoken_by>Speaker2</spoken_by>
<tone>normal></tone>
<spoken_text>Hi</spoken_text>
</response>
</conversation>

 

A rough analogy is the use of the Ethernet to connect devices. Many vendors describe their systems as open because they have an Ethernet port on their device. Purchasers discover that they need to use the same protocols to communicate. Thus XML may be used by more than one vendor to define a data transmission protocol but this does not mean that all XML protocols are alike.

So what does XML gives us? A structured way of defining a data communications protocol. The structure defines the following

  • Rules for XML tag names
  • Rules for dealing with white space
  • Rules for case sensitivity
  • Rules for character use
  • Rules for Document Type Definitions
  • Rules for Well-Formedness
  • Etc.

 

XML – An Example from the Chemical Industry

The Chemical Markup Language (CML) uses the structure of XML to define a method for defining molecules, the attributes and behaviors in such a way that an ‘average’ chemist can understand the definitions. Read more at http://xml.coverpages.org/cml.html

The fragment below is extracted from “caffeine.xml” on the site http://www.xml-cml.org/

 

<?xml version=”1.0″ ?>
– <!– <?xml-stylesheet type=”text/xsl” href=”generic.xsl” ?>
–>
– <document>
– <!– CML document – caffeine – karne – 7/8/00
–>
– <!– file converted from: MDL .mol
–>
– <cml title=”caffeine” id=”cml_caffeine_karne” xmlns=”x-schema:cml_schema_ie_02.xml”>
– <molecule title=”caffeine” id=”mol_caffeine_karne” convention=”mol”>
<formula>C8 H10 N4 O2</formula>
<string title=”CAS”>58-08-2</string>
<string title=”ACX”>I1001269</string>
<string title=”DOT”>UN 1544</string>
<string title=”RTECS”>EV6475000</string>
<float title=”molecule weight”>194.19</float>
<float title=”melting point” units=”degC”>238</float>
<float title=”specific gravity”>1.23</float>
<string title=”water solubility” units=”g/100 mL” convention=”g per 100 mL at 23 degC”>1-5</string>
<string title=”comments”>White powder or white glistening needles usually melted together. LIGHT SENSITIVE</string>
– <list title=”alternate names”>
<string title=”name”>1,3,7-Trimethylxanthine</string>
<string title=”name”>3,7-dihydro-1,3,7-trimethyl-1H-Purine-2,6-dione</string>
<string title=”name”>1,3,7-Trimethyl-2,6-dioxopurine</string>
<string title=”name”>eldiatric c</string>
<string title=”name”>organex</string>
<string title=”name”>1,3,7-trimethyl-2,6-dioxo-1,2,3,6-tetrahydropurine</string>
<string title=”name”>caffenium</string>
</list>
– <atomArray>
– <atom id=”caffeine_karne_a_1″ convention=”mol”>
<float builtin=”x3″ units=”A”>-2.8709</float>
<float builtin=”y3″ units=”A”>-1.0499</float>
<float builtin=”z3″ units=”A”>0.1718</float>
<string builtin=”elementType”>C</string>
</atom>
– <atom id=”caffeine_karne_a_2″ convention=”mol”>
<float builtin=”x3″ units=”A”>-2.9099</float>
<float builtin=”y3″ units=”A”>0.2747</float>

 

Links

Wikipedia- XML
XML Tutorial

XML FAQ
XML Projects
 

 

 

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