PACKAGES AND DATALINKS

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PACKAGES AND DATALINKS
How data is transmitted and stored

• SESSION 7

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THIS SESSION

• Earlier, we looked at
• XML
• The rationale behind XidML
• 3 of the simpler key elements
• Parameters and Instruments
• Now, we will look at
• Packages
• DataLinks
• Later, we will look at the remaining two key
  elements of XidML

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OVERVIEW

• Packages
• How data is moved around within the system
• Includes
• IRIG-106 PCM frames
• Ethernet
• MIL-STD-1553
• ARINC-429
• DataLinks
• Physical attributes of the connections within the
  system
• Includes
• Bit rate (ARINC-429)
• TTL vs. RS-422 (PCM)
• Response time (1553)
• Parity, bits, stop etc. (RS-232)

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THE SAMPLED DATA
Ive got a million different frames and data
structures I have to handlesometimes
simultaneously. I need to maintain a library of
data structures or packages.
XidML can record this information, independent of
a specific program/configuration
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XidML SCHEMA OSI REFERENCE MODEL
Parameters
PACKAGES describe how data is packaged to move
around the system
Packages
Instrumentation
Documentation
Addendum
Auxiliary Files
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PACKAGING

• Definition
• Describes the physical composition and structure
  of a data stream, communication Protocol or
  storage format
• Packages are used to describe bus protocols,
  communication protocols or storage formats
• IRIG-106 PCM data streams
• MIL-STD-1553 bus protocol
• IRIG Chapter 10 storage format
• Package definitions are stored in package
  libraries
• Can be further grouped into sub-categories

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PACKAGING (CONTD.)

• Package definitions can be reused more than once
• Reduces data redundancy
• Package definitions are separate from content
  and from the description of parameter and message
  placement
• Reduces data redundancy
• Increases data reuse

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Packages - SCHEMA
A set of packages
Optional element to allow packages to be grouped
(e.g. by aircraft configuration)
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Packages

• PackageSet element is a hook for many
  sub-schema that specify possible packages
• A package is a bundle of data or a protocol.
  e.g.
• IRIG-106 PCM frame
• MIL-STD-1553 Message
• Ethernet UDP packet
• IEEE1394 Message
• Data file recorded to memory
• Its also possible to add user or vendor specific
  packages
• XidML schema defines common packages

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XidML Packages
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Package EXAMPLE 1 PCM
Determines whether stream is synchronous or
asynchronous relative to global acquisition cycle
Determines the number of times per second the
package is transmitted or stored
A DataLink is a label for a channel that might be
used to transmit this PCM frame
The frame properties - size, shape etc.
The data in the frame (sub or super commutation
etc.)
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Properties OF A PCM Package

• FrameFormatIdentifier details of a frame
  parameter that identifies the frame
• MajorFrameProperties bits/minor, minor/major,
  fill pattern etc. etc.
• SynchronizationStrategy sync pattern, type of
  minor-frame identification etc.
• Modulation PCMCode, clock phase etc.

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Properties OF A PCM Package (CONTD.)
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Properties OF A PCM Package - Content

• Defines locations in frame
• Cross-references to a parameter in the Parameters
  element
• Allows single frame definition to be reused over
  and over
• Supports any type of frame structure

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EXAMPLE OF A 1553 Package
Determines whether stream is synchronous or
asynchronous relative to global acquisition cycle
Determines the number of times per second the
1553 package is transmitted or stored
A DataLink is a label for a bus that might carry
this message
This expands.
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1553 Package WITH SUBELEMENTS
Subelements for each message type
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RT TO RT IN MORE DETAIL
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A PCM Package
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A PCM Package(CONTD.)
These words are placeholders actual parameters
can be linked to them for a given
configurationwithout editing this file.
XidML strives to use the minimum amount of
information necessary to fully define an
attributewith no duplication or redundancy
(Image is a screen shot from XMLSpy)
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AN ETHERNET Package
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XidML SCHEMA OSI REFERENCE MODEL
Parameters
Packages
DataLinks

• DataLinks define paths for data moving around the
  system

Instrumentation
Documentation
Addendum
Auxiliary Files
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DataLinks - I

• The DataLinks element has two child elements
• DataLinkSet
• Contains a list of named child elements each
  representing a DataLink
• Names of DataLink elements must be unique
• DataLinks describe meta-data that is common to
  packages of the same type
• DataLinks describe physical attributes of a
  link
• A predefined set of DataLink schemas is included
  as part of XidML 2.0
• Other vendors can add their own DataLink schemas
  to a XidML file

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DataLinks - SCHEMA

• XidML provides common DataLink schemas
• Others can be added

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DataLink - EXAMPLE

• For PCM type refers to TTL or RS422 physical
  layer details
• For MEM we specify capacity and type

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USING DataLinks

• DataLinks are used
• To separate packages from the physical wire
• Connecting a set of 1553 messages to a DataLink
  permits multiple modules to be defined as
  monitors for that link easily.
• To reduce redundancy
• Rather than specify a bit rate every time an
  ARINC-429 message is defined, connect it to a
  DataLink and store the bit rate there.

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USING DataLinks (CONTD.)
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THIS SESSION COVERED

• Packages
• How data is moved around within the system
• DataLinks
• Physical attributes of the connections within the
  system
• Recap
• The PCM link is an RS-422 link and is a property
  of the DataLink
• The PCM code is a property of the Package
• The misses-to-lock is a property of the decoder
  Instrumentation
• Next, we will look at Algorithms

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END OF SESSION 7