SMART SENSORSSMART SENSORS

IEEE 1451.3IEEE 1451.3

Ramesh V.KandalamRamesh V.Kandalam

Dr.John SchmalzelDr.John Schmalzel

ECE Dept, Rowan University, 2005.ECE Dept, Rowan University, 2005.

OutlineOutline IntroductionIntroduction IEEE 1451 familyIEEE 1451 family 1451.3 Overview1451.3 Overview Objectives of 1451.3Objectives of 1451.3 1451.3 General Model1451.3 General Model 1451.3 Terms1451.3 Terms Data TypesData Types Smart Transducer Functional SpecificationSmart Transducer Functional Specification AddressesAddresses Operating StatesOperating States Data Sets, Messages and PacketsData Sets, Messages and Packets Triggering MethodsTriggering Methods TransducerChannel Type DescriptionsTransducerChannel Type Descriptions CommandsCommands

Initialization Commands Initialization Commands Operational CommandsOperational CommandsQuery-TEDS CommandsQuery-TEDS CommandsRead-TEDS Block CommandsRead-TEDS Block CommandsWrite-TEDS Block CommandsWrite-TEDS Block Commands

TEDS TEDS Meta-TEDSMeta-TEDS

TransducerChannel TEDSTransducerChannel TEDSCalibration TEDSCalibration TEDSText-Based TEDSText-Based TEDS

Manufacturer-defined TEDSManufacturer-defined TEDS

ConclusionConclusion

IntroductionIntroduction

Low-cost, networked smart sensors are developed for Low-cost, networked smart sensors are developed for diverse industry’s needs. diverse industry’s needs.

Interfacing the smart sensors to all of these control Interfacing the smart sensors to all of these control networks and supporting the wide variety of protocols networks and supporting the wide variety of protocols require very significant efforts.require very significant efforts.

A universally accepted transducer interface standard, A universally accepted transducer interface standard, the IEEE P1451 standard, is developed.the IEEE P1451 standard, is developed.

What is IEEE1451What is IEEE1451

IEEE 1451 is a family of proposed standards for IEEE 1451 is a family of proposed standards for "A Smart "A Smart Transducer Interface for Sensors and Actuators".Transducer Interface for Sensors and Actuators". Together Together these standards provide a single generic interface between a these standards provide a single generic interface between a transducer and external network, independent of the network transducer and external network, independent of the network protocol in use. protocol in use.

The goal is to separate the design of the sensors and actuators The goal is to separate the design of the sensors and actuators from that of the networking controller, and to make the from that of the networking controller, and to make the

network protocol transparent to the transducer.network protocol transparent to the transducer.

IEEE 1451 FamilyIEEE 1451 Family

1451.3 1451.3 OverviewOverview

Proposes a standard digital interface (TBIM) which can Proposes a standard digital interface (TBIM) which can connect multiple physically separated transducers in a connect multiple physically separated transducers in a multidrop configuration multidrop configuration

Digital Communication and Transducer Electronic Data Sheet Digital Communication and Transducer Electronic Data Sheet (TEDS) Formats for Distributed Multidrop Systems(TEDS) Formats for Distributed Multidrop Systems

Used in applications where transducers are distributed across Used in applications where transducers are distributed across an area in which it is not feasible to install an NCAP for each an area in which it is not feasible to install an NCAP for each transducer channeltransducer channel

ObjectivesObjectives Enable plug and play at the transducer level with Common Enable plug and play at the transducer level with Common

Communication interface for transducers which are physically Communication interface for transducers which are physically separatedseparated

Enable and simplify the creation of groups of networked smart Enable and simplify the creation of groups of networked smart transducerstransducers

Facilitate the support of multiple networksFacilitate the support of multiple networks

IEEE 1451.2IEEE 1451.2

http://www.sensorsportal.com/HTML/standard_3.htm

1451.3 Implementation1451.3 Implementation

http://www.sensorsportal.com/HTML/standard_3.htm

1451.3 partition of general model1451.3 partition of general model

http://www.sensorsportal.com/HTML/standard_3.htm

1451.3 1451.3 TermsTerms

Transducer Bus Controller (TBC): One on each NCAP to Transducer Bus Controller (TBC): One on each NCAP to communicate with multiple TBIMs. Supports multiple, time-communicate with multiple TBIMs. Supports multiple, time-synchronized data channels to occupy single transmission synchronized data channels to occupy single transmission medium (bus).medium (bus).

A TBC is the hardware and software in the Network Capable A TBC is the hardware and software in the Network Capable Application processor(NCAP) or host processor that provides Application processor(NCAP) or host processor that provides the interface to the transducer bus.the interface to the transducer bus.

The transducer bus provides the communications path between The transducer bus provides the communications path between an NCAP or host processor and one or more TBIM’s.an NCAP or host processor and one or more TBIM’s.

1451.3 1451.3 TermsTerms

Transducer Bus Interface Module (TBIM): A transducer node, Transducer Bus Interface Module (TBIM): A transducer node, like the STIM, but communicates with NCAP through multi-like the STIM, but communicates with NCAP through multi-drop transducer bus and TBC.drop transducer bus and TBC.

A TBIM is a module that contains the bus interface, signal A TBIM is a module that contains the bus interface, signal conditioning, Analog-to-Digital and/or Digital-to-Analog conditioning, Analog-to-Digital and/or Digital-to-Analog conversion and in many cases the transducer.conversion and in many cases the transducer.

A TBIM can range in complexity from a single sensor or A TBIM can range in complexity from a single sensor or actuator to units containing many transducers.actuator to units containing many transducers.

DATA TYPESDATA TYPESAll data types used throughout the remainder of this standard are defined in

subordinateSub clauses.

• Unsigned octet integer for counting(Symbol - U8C) This data type represents positive counting integers from 0 - 255.

• Unsigned octet integer for enumeration(Symbol - U8E) All 1-octet enumerations are unsigned integers, with a value between 0-255.

• Unsigned 16-bit integer for counting(Symbol - U16C) This data type is used to represent positive counting integers from 0-65535

• Unsigned 16-bit integer for field length(Symbol - U16L)Used to represent unsigned integers from 0-65535. When used to specify the length of a data block, the length field shall not include the length of the length field itself.

DATA TYPESDATA TYPES• Signed 32-bit integer(Symbol - S32)

Used to represent a signed integer from -2 147 483 648 to 2 147 483 647

• Unsigned 32-bit integer for counting(Symbol - U32C) Used to represent a positive counting integer from 0 to 4 294 967 295

• Unsigned 32-bit integer for field length(Symbol - U32L) Used to represent unsigned integers from 0 to 4 294 967 295. When used to

specify the length of a data block, the length field shall not include the length of the length field itself.

• Universal Unique Identification(Symbol - UUID) UUID is an identification field associated with the TBIM whose value is unique.

There shall be no requirement that the interpretation of the UUID reflect the actual place or time of the manufacture of TBIM. The use of time and location in the algorithm shall be used only to ensure uniqueness.

Smart Transducer Functional Smart Transducer Functional SpecificationSpecification

AddressesAddresses

Sixteen-bit addresses are used on the transducer bus.Sixteen-bit addresses are used on the transducer bus.

Concatenating the TBIM and the TransducerChannel number Concatenating the TBIM and the TransducerChannel number forms the 16-bit address.forms the 16-bit address.

The TBIM is assigned by the system as part of the discovery The TBIM is assigned by the system as part of the discovery process and forms the eight most significant bits of the process and forms the eight most significant bits of the address.address.

AddressesAddresses

Classes of Addresses

The commands addressed to the Global Address shall be received and honored by all the TBIM’s on the bus.

Commands issued to an AddressGroup shall be honored by all Transducer Channels that have been initialized as members of that AddressGroup, irrespective of the TBIM on which they reside.

AddressesAddresses

Commands issued to a TBIM apply to the TBIM as a unit.

Commands issued to a specific Transducer Channel apply to that Transducer Channel only

There are no commands defined that shall be honored when addressed to the TBC address.

PLUG AND PLAY CAPABILITYPLUG AND PLAY CAPABILITY

TBIM and TBC that are built must be able to be connected using a transducer bus and be able to operate without any changes to thesystem software.

No need for different drivers, profiles or other software changesto provide basic operation of the transducer.

Connectors and bus power supply voltages are recommended by this standard and not required makes it necessary for the user todetermine if a TBIM or TBC can be safely connected to a particularimplementation of the transducer bus.

Operating StatesOperating States

TransducerChannel Operating States

Structures used to store and transmit data There are three structures that are used to store and transmit data in this standard.

They are

• The data set,

• The message, and

• The packet.

Data sets All TransducerChannels operate with data sets. Three fields within the TransducerChannel TEDS define a data set.

The Maximum data repetitions field defines the maximum number of individual data samples in a data set.

The actual number of samples may be made lower than the number in the Maximum data repetitions field by the optional Set TransducerChannel Data Repetition Count command.

The second field is the Series increment field. This field is used to determine the interval between samples and it may be overridden by a manufacturer-defined command or an embedded actuator.

The third field is the Series units field. This field defines the units for the Series increment field. The implication of the Series units field is that the units of the Series increment field does not need to be time and that if this is the case the time interval between samples may not be uniform.

EXAMPLE—The Series units are degrees Kelvin and the Series increment is 0.5. This combination would cause a sensor to acquire data every 0.5 degrees. The samples would be at uniform temperature intervals instead of uniform time intervals.

Structures used to store and transmit data

Messages and packets

Messages may contain up to 65 520 octets plus 14 octets in headers.

The data link and physical layers of the protocol stack transmit packets.

If a message is too long to fit within a single packet, it is the responsibility of the Data Link Layer in the protocol stack to break messages down into multiple packets for transmission.

Enabling and disabling triggers

A TransducerChannel may have its ability to be triggered enabled or disabled by means of commands.

A trigger is a signal applied to a TransducerChannel or set of TransducerChannels to cause them to take a particular action.

Trigger methodsThere are two methods recognized by this standard to initiate a trigger.

Explicit triggers commanded by the TBC and

Events within a TBIM that may be used as triggers.

Trigger methods

Trigger messagesTrigger messages are sent from the TBC to one or more TransducerChannels

on a transducer bus.

A trigger message may be addressed to any of the following:

A TransducerChannel - applies to one TransducerChannel on one TBIM.

A TransducerChannel Proxy - It is an addressable resource within a single TBIM

that is capable of representing one or more TransducerChannels within that TBIM.

A TBIM - Triggers all TransducerChannels that are implemented on that TBIM.

Trigger methods

An AddressGroup - A trigger message issued to that AddressGroup triggers all

members of that AddressGroup.

The global address - A global trigger applies to all TransducerChannels in all

TBIMs on a given transducer bus. The system issues a global trigger by issuing a trigger message to the global address.

Events used as triggersEvents within a TBIM may be used as triggers.

An event used as a trigger may be formally implemented as an Event Sensor.

Trigger methodsContinued….

Nominal trigger logic

Simple TransducerChannel functional blocks

Trigger methodsContinued….

Trigger logic based on event recognition

Event sensor output used as a trigger

TransducerChannel type descriptions

The TransducerChannel types are: Sensor Event sensor Actuator

Sensor A sensor shall measure some physical parameter on demand and return digital data

representing that parameter.

On the receipt of a trigger the sensor shall start the collection and storing of a data set within the TBIM.

A sensor, in the operating state, shall respond to a read command by returning the appropriate data set.

TransducerChannel type descriptions

Event sensor An event sensor determines the level of some physical phenomena but

determines when a change of state has occurred. The TEDS definition for an event sensor is the same as for any other

transducer.

Actuator An actuator shall cause a physical or embedded output action to occur. The actuator output state changes to match the appropriate data set when a

triggering event occurs.

Hot-swap capability

Hot-swap capability exists within the system on two levels.

It shall be possible to disconnect a TBIM from the bus or to connect a TBIM to the bus without powering down the bus and without damage to either the TBIM being inserted or anything else connected to the bus.

Commands

Commands are divided into two categories,

Standard and Manufacturer-defined.

The most significant octet shall be used to define the class of the command.

The least significant octet, called the function, shall identify the specific command within the class.

For example, if the most significant octet defines the Read TEDS block

class of commands, the least significant octet then specifies the TEDS to be read.

Initialization commands

The initialization class of commands is used to set up a TBIM.

A TBIM, TransducerChannel or TransducerChannel proxy only responds to commands in this class when in the halted state.

Commands in this class that may be issued to both a TransducerChannel and a TranducerChannel proxy

Set TransducerChannel data repetition count

• Used to change the number of data samples in a data set to a number between one and the maximum number found in the maximum data repetitions field of the TransducerChannel TEDS.

• If an acknowledgment is required for this

command, the reply shall contain the 32-bit status word for the TBIM in the data field

Initialization commandsContinued…

Read TransducerChannel data repetition count

Used to read the actual number of TransducerChannel pre-trigger counts that are assigned for the addressed TransducerChannel.

Read AddressGroup assignment

This command is used to read all of the AddressGroups to which the addressed TransducerChannel or TBIM is assigned.

Operational commands

Operational commands are the class of commands that are expected to be used in the collection and processing of data.

Commands in this class may be issued at any time after an alias is assigned to the TBIM.

Query data block

This command is used to define to the TBC the information required to read or write large data

blocks

Operational Commands

Operational commandsContinued…

Read TransducerChannel data block

The reply to a Read data block command uses the Reply Protocol

The size of the response is limited by the smaller ofeither the ‘‘Maximum block size of response’’ fieldin the Read data block or the maximum size block that the TBIM can transmit.

Write TransducerChannel data block

This command is used to write large data blocks intoa TBIM or TransducerChannel.

The reply to a write data block command shall contain two octets. These two octets shall represent a16-bit number giving the number of octets received.

Query TEDS commands

This class of commands is used by the TBC to solicit information required to read or write the TEDS.

Some TEDS apply to the entire TBIM while others to a specific TransducerChannel.

Query TEDS commands may not be addressed to AddressGroups or globally.

The TBIM is required to provide a reply to all Query TEDS commands

When the Unsupported TEDS attribute is set, the TBIM shall return a zero for the Current size of the TEDS and the Maximum TEDS size fields.

Query TEDS response in the data field

TEDS attributes

Read TEDS block commands

To read a TEDS, the TBC uses this class of commands.

The function field of the command shall contain the TEDS access code,

There are arguments for this command; the maximum block size that the bus controller supports, and the offset into the TEDS to begin reading.

The size of the response is limited by the smaller of either the Maximum block size of response field in the Read TEDS block command or the maximum size block that the TBIM can transmit.

The reply to a Read TEDS block command uses the Reply Protocol

The reply to a Read TEDS block command shall contain a variable number of octets in the data field.

Arguments for a read TEDS block command

Read TEDS block response

Write TEDS block commands

This class of commands is used to write the TEDS in a TBIM.

The Write TEDS block command uses the Command Services Protocol. The total number of octets in the message (including protocol wrappers) shall not exceed the value reported by the TBIM in the Maximum block size for Write TEDS block command field of the Query TEDS command.

A Write TEDS block command shall create a new TEDS if one does not already exist with that function. If the TBIM is not designed to allow the TEDS to be created, the Write TEDS block command shall not write any data into TEDS memory because the TEDS is unsupported.

TRANSDUCER ELECTRONIC DATA TRANSDUCER ELECTRONIC DATA SHEET(TEDS) SPECIFICATIONSHEET(TEDS) SPECIFICATION

TEDS are blocks of information that are intended to be stored TEDS are blocks of information that are intended to be stored in non-volatile memory with a TBIM.in non-volatile memory with a TBIM.

When the TEDS are stored in some location than TBIM then When the TEDS are stored in some location than TBIM then they are called as Virtual TEDS.they are called as Virtual TEDS.

The manufacturer of the TransducerChannel provides the The manufacturer of the TransducerChannel provides the virtual TEDS in some electronic form.virtual TEDS in some electronic form.

It is users responsibility to link the data information that is It is users responsibility to link the data information that is guaranteed to be available from the TBIM, i.e., UUID(Unique guaranteed to be available from the TBIM, i.e., UUID(Unique Identification ID).Identification ID).

The NCAP or the host processor provides this service if it is The NCAP or the host processor provides this service if it is used.used.

General format for TEDS

TEDS length -- total number of octets in the TEDS data block plus the two octets in thechecksum.

Data block -- This structure contains the information that is stored in a specific TEDS.

Checksum -- The checksum shall be the one’s complement of the sum (modulo 216)of all preceding octets, including the initial TEDS length field and the entire TEDS data block.

Meta-TEDS

The Meta-TEDS is accessed using a

• Query TEDS command,

• Read TEDS block command,

• Write TEDS block command,

or

• Update TEDS command with a

destination address of a TBIM.

Meta-TEDSMeta-TEDS

The Meta-TEDS should be implemented as Read-only to prevent an end user from modifying its content.

TransducerChannel TEDS

This is a required TEDS.

The function of the TransducerChannel TEDS shall be to make available at the interface all of the information concerning the TransducerChannel being addressed to enable the proper operation of the TransducerChannel.

TransducerChannel TEDS

This TEDS is accessed using a • Query TEDS command, • Read TEDS block command, • Write TEDS block command, or • Update TEDS command with a destination address of a TransducerChannel.

Calibration TEDS The Calibration TEDS is

accessed using a

• Query TEDS command,

• Read TEDS block command,

• Write TEDS block command, or

• Update TEDS command

with a destination address of a TransducerChannel.

Text-based TEDS The function of these TEDS is to

provide information for display to an operator.

There are five TEDS that fall into this category.

Meta- Identification TEDS,

TransducerChannel Identification

TEDS,

Calibration-Identification TEDS,

Commands TEDS

Location and Title TEDS.

Manufacturer-defined TEDS& PHY TEDS

Manufacturer-defined TEDS may be in any format required by the manufacturer’s application software.

For a manufacturer-defined TEDS that are being sent to the TBIM, the system shall take the information, apply the length field and checksum fields and transmit it to the TBIM.

The PHY TEDS is a required TEDS.

The function of the PHY TEDS shall be to make available at the interface all of the information needed to gain access to any channel, plus information common to all channels.

Things we have seen till now…Things we have seen till now…

Implementation model of IEEE 1451.3 Implementation model of IEEE 1451.3 Terms (TBC and TBIM) in IEEE 1451.3Terms (TBC and TBIM) in IEEE 1451.3 Data TypesData Types AddressesAddresses Operating StatesOperating States Data Sets, Messages and PacketsData Sets, Messages and Packets Enabling and Disabling the triggersEnabling and Disabling the triggers Triggering MethodsTriggering Methods TransducerChannel DescriptionsTransducerChannel Descriptions CommandsCommands TEDSTEDS Meta-TEDSMeta-TEDS

TransducerChannel TEDSTransducerChannel TEDS Calibration TEDSCalibration TEDS

CONCLUSIONCONCLUSION

The Standard has provided the beginning of a consistent set of tools to address the issue of displaying data in a standardized way.

By providing a way for a set of base units to be incorporated into the transducer, the working group has standardized the way that the units are represented in the TEDS.

A transducer that is built and calibrated per the standard should be able to plug into any system.

REFERENCESREFERENCES

http://www.completetest.com/IEEE1451_overview.htmhttp://www.completetest.com/IEEE1451_overview.htm

http://www.sensorsportal.com/HTML/standard_3.htmhttp://www.sensorsportal.com/HTML/standard_3.htm

http://www.tarallax.com/ieee1451.htmlhttp://www.tarallax.com/ieee1451.html

www.sensornet.gov/ftbragg/IEEE1451_Sensor_Standard_Fort-Bragg.pdfwww.sensornet.gov/ftbragg/IEEE1451_Sensor_Standard_Fort-Bragg.pdf

www.sensorsportal.com/HTML/DIGEST/july_04/E_05.pdfwww.sensorsportal.com/HTML/DIGEST/july_04/E_05.pdf

www.ieee1451.nist.gov/group3.htmlwww.ieee1451.nist.gov/group3.html

www.standards.ieee.org/catalog/olis/im.htmlwww.standards.ieee.org/catalog/olis/im.html

IEEE Standard for a Smart Transducer Interface for Sensors and Actuators—Digital Communication and Transducer Electronic Data Sheet (TEDS) Formats for Distributed Multidrop Systems

Questions

AssignmentAssignment

Calculate the time of a sample in a data set. Briefly describe and show the formula used in the calculation.

Hint: Chapter 5 of IEEE Standard for a Smart Transducer Interface for Sensors and

Actuators—Digital Communication and Transducer Electronic Data Sheet (TEDS)

Formats for Distributed Multidrop Systems