IEEE 1451'4 Overview

1
IEEE 1451.4 Overview

• Smart Sensors - 2005
• Prof Dr.Schmalzel
• Presented by Sathya Bandari
• Confesor Santiago

2
Overview

• Introduction to 1451.4
• Theory
• Applications Usages
• TEDS structure
• TEDS templates
• Usage of template
• System Details
• Template with TDL
• Interfaces
• G2
• Portable PDA
• Virtual TEDS
• Extensibility
• CEDS
• Conclusion

3
Why IEEE Standards

• The IEEE-NIST 1451 family of standards is a set
  of open standards that define interfaces for
  sensors and actuators to communicate with
  processors.
• These standards enable more features, bandwidth
  ,lower costs, well adapted and creates greater
  deployments of networked smart sensors at reduced
  costs.

4
Why IEEE 1451.4

• A key feature of this standard is to provide for
  analog and digital signals sharing the same set
  of wires in a Mixed Mode Interface.
• This standard focuses on the front end of the
  smart transducer model and provides for a
  low-cost, memory lean, TEDS model.
• It also enables the use of existing cabling to
  send analog sensor signals from remote
  transducers.

5
Definition

• IEEE 1451.4 is standard for adding plug and play
  capabilities to analog transducers.
• The underlying mechanism for plug and play
  identification is the standardization of a
  Transducer Electronic Data Sheets (TEDS)

6
IEEE 1451.4 Plug Play Sensors
7
Plug play Sensor with Embedded TEDS Info

• IEEE 1451.4 is a standard that defines how analog
  transducers can inherit self-describing
  capabilities for simplified plug and play
  operation.
• The standard defines a mixed-mode interface that
  retains the traditional analog sensor signal, but
  adds a low-cost serial digital link to access a
  transducer electronic data sheet (TEDS) embedded
  in the sensor for self-identification and
  self-description.

8
Components Of Dot 4

• TEDS
• Mixed Mode Interface

9
Component 1

• What is the need for TEDS?
• For sensors self-Identification
• IEEE 1451.4 defines a standard format for TEDS
  data to be embedded into plug and play
  transducers.
• IEEE 1451.4 TEDS contains the manufacturer,
  model number, and serial number for the
  transducer. Most TEDS also describe the important
  attributes of the sensor or actuator, such as
  measurement range, sensitivity, temperature
  coefficients, and electrical interface

10
Components - II

• Mixed Mode Interface
• Defines two types of Interface
• Class 1 Two wire interface
• Class 2 Multi wire Interface

11
How does MMI defines Classes

• Class 1 minimizes system wiring, use of a single
  connection for both analog signals and data.
• Ex Accelerometers and Microphones containing
  current operated amplifiers.

12
Class 2

• Class 2 allows for analog and digital data to be
  transferred via separate connections, in
  applications not adaptable to a shared
  connection.
• Applications include very impedance sensors (PH
  glass electrode), Actuators and Sensors of the
  4-20mA variety, Bridge Transducers, Thermistors
  or RTD Temperature Sensors.

13
Class 1 Two Wire Interface

• Class 1 defines sequential sharing of a single
  connection, comprised of two wires, by analog and
  digital signals.
• An analog signal is defined as a positive voltage
  with respect to signal return.
• while digital data is transmitted as a negative
  voltage. For Class 1, zero volts is a logic zero
  and 5 volts is a logic one.

14
Class 2 Multi Wire Interface

• Class 2 defines a data connection independent of
  the analog signal.
• TEDS to be included in applications which are not
  adaptable to shared operation between data and
  analog signals.
• Ex bridges, thermocouples, current operated
  transducers, etc., which cannot have a switching
  diode in the analog signal connection.

15
MMI Data Transfer

• Data transfer in MMI is implemented using 4
  command pulses.
• They are
• Reset
• Write-one
• Write-zero and
• Read

16
MMI Data Transmission Waveforms

• Implemented by the commands made up of 4 pulse
  intervals
• Reset
• Write-one
• Write-zero and
• Read.
• Applied in sequence defined for the TEDS node
  device.

17
MMI Data Transfer (Continued)

• Transfer always begins with a reset interval,
  followed by a ROM command consisting of read and
  write sequences, then by a RAM command, comprised
  of read and write sequences.
• The two waveforms describe the timing diagrams
  for Class 1 with pulses between zero and negative
  5 volts.
• For class 2 signal polarity is reversed with
  pulses between zero and positive 5 volts.

18
In General

• IEEE 1451.4 defines a physical connection
  (Mixed-Mode Interface, or MMI) that is
  alternately used for TEDS data and analog
  signals, on either 2, 3 or 4 wires.
• This adapts the Standard for use with a wide
  variety of sensors and actuators.

19
Compatibility With Legacy Systems

• P1451.4 Transducers with TEDS are compatible
  with legacy data acquisition systems by utilizing
  existing analog connections.
• With the plug in of legacy sensors P1451.4
  transducer behaves as a digital communication
  mode
• Legacy systems can be updated to support P1451.4
• Hardware Additional circuitry can be hooked up
  at the front-end to control P1451.4 Transducers
  and decode the TEDS.

20
Compatibility

• Patch Panel It can be introduced b/w P1451.4
  transducers and legacy systems to send out
  interrogation signals to activate the digital
  mode.
• It can also decode and upload the digital TEDS
  data to the controller.
• Firmware/Software The embedded controller or the
  software in the legacy system can extract the
  TEDS data from the waveform memory after power up
  which requires no modification of legacy systems
  or additional hardware.

21
Its Usage

• Due to its use of templates, IEEE 1451.4 allows
  TEDS data to be stored in memories that are
  physically small, extending the use of the
  standard to small lightweight transducers of many
  descriptions.
• Templates may be written for transducers not yet
  defined in the template library contained in the
  standard, by using the TDL.

22
Advantages

• Use of very small memories through the use of
  templates.
• Templates define the significance and units
  associated with the stored data and the mapping
  of the data in memory.
• Templates guides in packing and unpacking the
  data, new templates can be written in the
  Template Description Language (TDL).
• Allow interoperation of transducers and control
  systems of different manufacturers.

23
Advantages (Continued)

• Allow the use of existing control system
  installations.
• Goal of TEDS is to use in every form of
  Transducer.
• Allow transducers to share a common bus, reducing
  wiring cost and complexity.
• Increase the usage of existing networks.

24
Importance of TEDS

• Identification Parameters
• a. Manufacturer name
• b. Model number
• c. Series number
• d. Revision number
• e. Date code
• Device Parameters
• a. Sensor type
• b. Sensitivity
• c. Bandwidth
• d. Units

25
TEDS Importance

• Calibration Parameters
• a. Last calibration date
• b. Correction engine coefficients
• Application Parameter
• a. Channel identification
• b. Channel grouping
• c. Sensor location and orientation

26
IEEE 1451.4 Summary

• IEEE 1451.4 provides plug and play" for analog
  sensors via simple self-identification
• does not solve digital (network) sensor
  connectivity
• Today, applies primarily to wide range of
  traditional" measurement systems that rely on
  analog sensor interfaces
• Provides easier setup and configuration
• Management of sensor data, calibration info,
  etc.
• Will provide useful component of 1451 systems
  wherever analog interfaces are required
  (TIM-to-sensor)

27
Sensors currently Available
28
TEDS structure
IEEE 1451.4 TEDS data system block diagram
29
Basic TEDS

• Contents
• Uses 64 bits
• Contained in non-volatile memory.
• Use checksum to ensure integrity

30
TEDS template

• A template describes the memory structure of TEDS
  data that contains information about the identity
  of the transducer and transducer specific data.
• A Template ID at the beginning of each template
  identifies the template.
• The number of bits used to identify the template
  is unique for the descriptor of the template.

31
TEDS template
IEEE standard templates - NI.com
32
TEDS template

• Written in the Template Description Language
  (TDL) and templates reside in the Transducer
  Block (T-Block).
• A T-Block is a software object describing the
  IEEE 1451.4 Transducer.
• It resides in the NCAP, which is the master
  device (e.g., an instrument or data acquisition
  system).
• The T-Block is used to access, decode, and encode
  TEDS using TDL.
• Templates available as one or more 8-bit ASCII
  text template description files with the
  extension .tdl.

33
TEDS template

• The template structure is designed with the main
  objective to use small-sized memory in an
  efficient manner.
• The first action in order to eventually read the
  content of the TEDS on an interface is to switch
  to Digital Mode and initialize the bus
  communication.

34
Template Description Language

• Using TDL, each template defines the bitmapping
  of its associated TEDS.
• Storage of relevant details in the TEDS
• Need to decode those details in a template
• User assured data can be retrieved, if
• Have appropriate TEDS
• A parser capable of interpreting TDL.
• Overcomes difficulties in providing either new
  transducers or upgrades to existing transducers

35
Template Description Language
These commands define the beginning and end of a
template.
1451.4 - IEEE Standard for A Smart Transducer
Interface for Sensors and Actuators
36
Template Description Language
1451.4 - IEEE Standard for A Smart Transducer
Interface for Sensors and Actuators
37
Template Description Language

• TDL also provides commands
• (not limited to list)
• Access Levels
• Spacing
• Alignment
• Select Cases and Cases
• StructArray
• Properties

38
Template Description Language

• Access Levels
• Provide a level of security for the data.
• Different users should only be able to write data
  if they have appropriate access.

1451.4 - IEEE Standard for A Smart Transducer
Interface for Sensors and Actuators
39
Template Description Language

• Spacing Command
• Program displays a line to visually separate two
  commands

• Align Command
• Realignment of the input pointer to the TEDS
  along word boundaries

1451.4 - IEEE Standard for A Smart Transducer
Interface for Sensors and Actuators
40
Template Description Language

• SelectCase and Case Command
• Provide the ability to use bits in the TEDS to
  determine different cases
• Syntax

1451.4 - IEEE Standard for A Smart Transducer
Interface for Sensors and Actuators
41
Template Description Language

• StructArray Command
• Allows the creation of a set of properties
  treated as a single structure as well as the
  ability to dynamically create an array by reading
  the size of the array from the TEDS.
• Syntax

1451.4 - IEEE Standard for A Smart Transducer
Interface for Sensors and Actuators
42
Template Description Language

• Properties commands
• Identified by a ()
• Provides the mechanism for assigning transducer
  specific values to the appropriate properties
• When a StructArray command is parsed, the number
  of bits indicated by ltnumber_of_bitsgt is read
  from the TEDS.
• The ltproperty_listgt is then read the number of
  times indicated by this initial value.

43
Template Description Language

• StructArray command with properties

1451.4 - IEEE Standard for A Smart Transducer
Interface for Sensors and Actuators
44
Template Description Language

• Using subproperties to extend TEDS

Thermocouple TEDS Template (ID36) - NI.com
45
Bridge Sensor TEDS Template (ID33) - NI.com
46
Interfacing

• User wants to view contents of the TEDS
• Use of software to interface between the human
  user and the embedded TEDS

47
Interfacing

• Some examples of interfaces
• G2s Graphical User Interface Development
  Environment (GUIDE)
• Endevco's new TEDS Reader

48
G2s GUIDE

• You construct a GUIDE user interface using
  graphical components called UIL controls.
• GUIDE supports different classes of UIL controls
  for different purposes
• Some classes of UIL controls, such as edit boxes,
  buttons, and scroll areas, enable users to view
  and edit the data stored in object attributes.
  The different classes are suitable for viewing
  and editing different types of data.
• Other classes of UIL controls, such as borders
  and separators, enable you to organize a user
  interface visually.

49
G2s GUIDE

• In a G2 knowledge base you can have defined class
  type of different TEDS
• Assigned attributes
• Users can read/edit these attribute values
  directly in the attribute tables of G2 objects.

50
G2s GUIDE
TEDS Tabbed Interface developed in G2
51
G2s GUIDE

• Advantages
• You can validate the changes that users make to
  attribute values, using criteria that you
  specify.
• You can specify the format used to display
  attribute values.
• You can process attribute values before you
  display them in a dialog.
• Not only interfaces data, but provides capability
  of creating processes and procedures.

52
Endevco's PDA TEDS Reader

• Endevco's new TEDS Reader is a portable
  engineering tool that enables users to quickly
  and easily review the full contents of any
  embedded IEEE 1451.4 TEDS using a PDA
• Using, Dell Axim X3 PDA (pocket PC) as its
  control/readout device, the system displays the
  contents of the TEDS memory chip located inside
  the transducer
• Includes important information such as
  sensitivity, location and calibration
  coefficients.
• The TEDS Reader shows the entire transducer data
  sheet in full detail, in contrast to similar
  devices that only read certain lines of a
  template.

53
(No Transcript)
54
Virtual TEDS

• A Virtual TEDS file is stored on a local computer
  or a web-accessible database instead of on an
  EEPROM.
• This enables the huge installed base of legacy,
  analog sensors to realize the benefits of TEDS
  without being retrofitted with an embedded
  EEPROM.
• Virtual TEDS are also valuable in applications
  where sensor operating conditions prevent the use
  of any electronics, such as EEPROMs, in the
  sensor.

55
Virtual TEDS
Virtual TEDS Accessible via a Web Interface
56
Virtual TEDS

• Where can I get Virtual TEDS?
• Virtual TEDS are available for download
• ni.com/sensors

57
TEDS in 1451.0

• IEEE p1451.0 is defined for the transfer of
  digital information between modules in a system.
• The IEEE p1451.0 TEDS are used to describe the
  entire TIM including the transducer, signal
  conditioner and data converters.
• To use an IEEE 1451.4 device with an IEEE p1451.0
  compatible device requires the appropriate signal
  conditioner for the transducer and an IEEE Std.
  1451.4 TEDS Translator.

58
TEDS in 1451.0

• The TEDS Translator is required to combine the
  contents of the IEEE Std. 1451.4 TEDS with the
  characteristics of the signal conditioner to
  allow the IEEE p1451.0 TEDS to describe the
  overall TIM.
• Both sets of TEDS are described in the standards
  for the family members but the details of how to
  combine the TEDS is not covered in any of the
  standards

59
TEDS in 1451.0
Generic format for any TEDS IEEE P1451.0
60
TEDS in 1451.0

• All TEDS prepared by a transducer manufacturer
  use a Type/Length/Value (TLV) data structure
• In the case of Text-based TEDS uses
  Type/Length/Value (TLV) data structure

Definition of the Type/Length/Value structure
IEEE P1451.0
61
TEDS in 1451.0

• Four TEDS that are required for all TIMs
• Meta-TEDS
• Make available at the interface all of the
  information needed to gain access to any
  TransducerChannel
• TransducerChannel TEDS
• Gives detailed information about a specific
  transducer
• Users transducer name TEDS
• Intended to be used to provide a place for the
  user of the transducer to store the name by which
  the system will know the transducer
• PHY TEDS
• Dependent upon the physical communications media
  used to connect the TIM to the NCAP and is not
  defined in the standard although the method of
  accessing it is defined
• All others are optional

62
TEDS in 1451.0

• Others TEDS include
• Calibration TEDS
• Provides the calibration constants necessary to
• Convert the output of a sensor into engineering
  units
• Convert an engineering units value into the form
  required by an actuator
• Frequency Response TEDS
• Uses a table to provide the frequency response
  of the TransducerChannel
• Transfer Function TEDS
• Describes a way to link a series of individual
  transfer functions together to describe the
  frequency response of a TransducerChannel in an
  algorithmic form.

63
TEDS in 1451.0

• Other TEDS include (cont)
• Text-based TEDS
• Family of TEDS that provide text based
  information about a TIM or TransducerChannel.
• One or more languages.
• Commands TEDS
• Text based TEDS that provides a way for the
  manufacturer to specify additional commands
  beyond those included in the standard.
• Identification TEDS
• 3 Text-based TEDS from 1451.2 lumped together

64
TEDS in 1451.0

• Other TEDS include (cont)
• Geographic location TEDS
• Contains static geographic location information.
• Expected to be written by the user to indicate
  the location at which the TIM is installed
• End user TEDS
• Similar to previously mention User transducer
  name TEDS
• Manufacturer defined TEDS
• Allows manufacturer to define TEDS that are not
  in this standard.
• Use and structure is left up to manufacturer
• Not required to make accessible to the user

65
TEDS in 1451.0

• Since the Meta-TEDS is the only TEDS in IEEE Std.
  1451.2-1997 and 1451.3-2003 that contains TEDS
  version information it is necessary when using
  that standard to read the Meta-TEDS before
  attempting to read any other TEDS.

66
TEDS in 1451.0

• Meta-TEDS access
• Query TEDS
• Used by the NCAP to solicit information required
  to read or write the TEDS.
• Read TEDS segment
• Used to read a TEDS into the NCAP
• Write TEDS segment
• Used to write a part of the TEDS
• Update TEDS
• Used to cause a TEDS that was previously written
  into a TransducerChannel to be verified and
  copied into non-volatile memory

67
Adding New IEEE templates and TDL items

• IEEE Registration Authority
• Act as the authoritative and exclusive
  clearinghouse for the maintenance of these items
• Processing of applications for new items
• Publishing of the complete list of items
• List made available - no charge

http//standards.ieee.org/regauth/1451/templateTDL
/request3.html
68
CEDS

• ISHM addresses the health management of systems.
  Complexity comes manifold as it needs to address
  a large number of items such as actuators, pumps,
  pipes, instruments, sensors, and functional
  processes called components for ISHM framework.

69
CEDS UML Diagram
70
Assignment

• Finds TEDS for simple transducer?
• Discuss extension TEDS based on your
  work/research area?