Basics of Hart

7/30/2019 Basics of Hart

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Ach ieving Digi tal Integrat ion

Using the HART Protoco l

Ach ieving Digi tal Integrat ion

Using the HART Protoco l

Unleashing the Power of HART

in Your System


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COMMUNICATION FOUNDATIONHART Copyright - HART Communication Foundation, 2002Page 2 of 59

Current Situation

nAll industry users working to: Improve Process Operations

Better Manage Plant Assets

Increase System Availability/Reliability

n

Many faced with declining budgets andpressure to do more with less

nMuch of the solution may already be in your plant Much of the Power is already in your smart field devices

enabled by HART technology

New control system interfaces leverage the intelligence in your

HART smart devices to deliver continuous Real-TimeDiagnostics and much more!


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Things You May Know About HART

n Most smart instruments use HARTCommunication

n HART smart field devices are usedinterchangeably with traditional 4-20mAanalog only units

n Hand Held Communicators are often used

to perform device set-up, calibration,commissioning and periodic maintenance

n PC-based instrument management tools canremotely communicate with HART devicesto manage calibration and other instrumentparameters from central locations

(instrument shop or control room)

HART = Saving s in Ins tallation & MaintenanceHART = Savings in Instal lat ion & Maintenance


4/59


n All HART smart devices provide processdata for plant operation continuously - 24/7

n HART communication provides access to alldevice data simultaneous with the 4-20mAanalog signal being used for control

n Diagnostic status information pertaining to

the health of the field device and quality ofthe 4-20mA signal is part of every message

n The Primary Variable (PV) is transmitted as a4-20mA signal and also as a digital value

n Many devices are Multi-Variable and havemeasured or calculated process variables in

addition to the PV

This Data is Valuable$$$

I/OI/O

ControlControl

HMIHMI

ERPERP

CMMSCMMS

H

ART

DATA

HARTHART

Field DevicesField Devices

Things You May Not Know About HART


5/59


Worldwide Installed Base

1%

12%

13%

48%

26%

HART Fieldbus Proprietary 4-20mA + Pneumatic

Smart Non - Smart

40-45 Million Devices

Source - ARC Advisory Group, Dedham, MA

Field DevicesField Devices--Press, Temp , Flow, Level, Valve Pos it ioners, An alyt icalPress, Temp , Flow, Level, Valve Posit ion ers, Analyt ical


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Worldwide Pressure Transmitter Outlook

HART HARTHART

Proprietary Proprietary

Conventional Conventional Conventional

AllFieldbusses

0

200

400

600

800

1000

1200

1400

1600

1800

2000

2001 2003 2005

UnitShipmen

ts(Thousands)

Source: 2001 Pressure Transmitter Worldwide Outlook Study

ARC Advisory Group, Dedham, MA USA

The Ins tal led Base of HART is Huge andThe Ins tal led Base of HART is Huge and

It wi l l cont inue to grow for a long t ime to come !It wi l l cont inue to grow for a long t ime to come !


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Part-TimeCommunication

FULL-TIME CommunicationIntegrated with Plant Systems

Device Set-up

Commissioning

Troubleshooting

100%

RELATIVEVA

LUE

Savings/Ben

efits

0% 100%

100%

Lim ited Benefit

ValueGap$$$

Online Real-Time Diagnostics

for proactive action

Validate accuracy of control

informationFull access to multi-variable

instrument information

ERP/CMMS Integration

Unleash the POWERof Your HART Smart Instruments


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I/OI/O

ControlControl

HMIHMI

ERPERP

CMMSCMMS

HARTHART

Field DevicesField Devices

HART Digital Integration

n

HART Communication integrated withplant control and safety systems

n Systems communicate with HARTdevices full time - analog + digital

n Operators alerted to impendingproblems before negative impact tothe process

Accuracy of data exchange betweenfield device and control systemvalidated continuously

Any deviation between field deviceand system (loop current, rangevalues, etc) detected immediately

Real time device diagnostics

n Additional process data in Multi-Variable devices used to improveplant operation


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HART BasicsHART Basics

An Introduction to the HART Protocol


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COMMUNICATION FOUNDATION

HART Copyright - HART Communication Foundation, 2002Page 10 of 59

What is HART ?

HART in a backw ard com patible enhancement to 4-20mAinstrumentation that al lows two way communication w i th

smart, mic ropro cesso r-based field devices.

n

HART Characteristics Simultaneosly supports two communications channels 4-20mA "analog" communications and

Modulated two-way "digital" communications.

Extensive Standardized Application Layer Data Device status and diagnostics;

Cyclical process data including: floating-point digitalvalue,engineering units and data quality / status; and

Field devices can continuously publish their process data.

Standardized Operating procedures (e.g.,for loop test, currentloop re-ranging and transducer calibration).


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The HART Specifications

nCollection Of Specifications Easy-to-Read Language

Consistent and well-defined terms

Controlled by HART Communication Foundation

nProvide Clear Complete Definition

of the HART ProtocolnOpen and Available to Anyone

HART Field CommunicationsProtocol Specification

HCF_SPEC-12, Revision 6.0

Data Link LayerSpecification


Command SummarySpecification


Universal CommandSpecification


Common Practice CommandSpecification


Device Families CommandSpecification.


Common TablesSpecification


Block Data TransferSpecification


Command Response CodeSpecification


FSK Physical LayerSpecification


The Protoco l

Physical Layer

Data Link Layer

Appl icat ion Layer

C8PSK Physical LayerSpecification

HCF_SPEC-60, Revision 1.0Organizat ion o fOrganizat ion of

Specif icat ionsSpecif icat ions


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Establishes Data Packet Structure,Framing, Error Detection, Bus Arbitration

Data Link2

Mechanical / Electrical Connection.Transmits Raw Bit Stream

Physical1

End to End Routing of Packets. ResolvingNetwork Addresses

Network3

Provides Network Independent,

Transparent Message TransferTransport4

Connection Management Services forApplications

Session5

Converts Application Data BetweenNetwork and Local Machine Formats

Presentation6

Provides the User with Network CapableApplications

Application7

OSI Layer Function

Secure Data Exchange; Token PassingNetwork; Multiple hosts and field devices.

Modulated Digital Signal. Simultaneous4-20mA and HART Communications

Pre-defined Data Types; StandardizedStatus, Process Data and Procedures

HART

HART Protocol Layers

nUses OSI Reference Model as a guidenSpecifications promote interoperability

Requirements in each layer clearly specified

HART Compatible devices must support all layers


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HART Physical Layer

HART allows addi t ional informationto be carried on thesame pair of wires with the 4-20 mA Analog Signal

Simul taneous ly and Transparent ly


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Physical Layer Features

n

2 Communications Channels1 Pair of Wires Digital Data Modulated on the Analog 4-

20mA Current Loop

Simultaneous and TransparentCommunications

n Standard 4-20mA wiring

n Backward Compatible With 4-20mAAnalog Instrumentations and Systems Allows HART Capable Instruments to be

added to existing systems

HART Capabilities can be utilizedincrementally

4-20mA Replacement Instrument Commissioning, Maintenance

Continuous Real-time Communications

Full Digital Integration

2200 Hz0

1200 Hz1

+0.5mA

-0.5mA

HART FSKHART FSK


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Two Communications Channels

n Channels Separated in Frequency Like Channels on a Television

Physical Layer Specification Ensures channel separation

Ensures simultaneouscommunication

n 4-20mA "Analog" Channel One-way communication of one

process value

4-20mA Analog support large part

of Protocol Specifications Simple Low Pass Filter isolates 4-

20mA signal HART looks like noise to most

existing systems.

4-20mASignal Band HART SignalBand

25Hz 10KHz500HzDC

n HART "Digital" Channel Two-way Communications

Compliments 4-20mA

Based on Analog TelephoneModems

Long Cable Runs

High Noise Immunity

You can "hear" HART


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HART Physical Layer Rules

Networks must have at least one, (andtypically) only one, low impedance device.Note: Total loop resistance must be between170 and 600 Ohms

A network must have no more than onedevice varying the 4-20ma signal.

Only one secondary device is allowed.

Cable run lengths to 3000m for single paircable and 1500m for multi-conductor cablesis typical.

Note: Actual length depends on the number ofmulti-dropped field devices and the quality ofthe cable used.

Low capacitance shielded twisted pair cableis stongly recommended.

Note: HART has been successfully used overpoor quality, unshielded wiring.

Linear power supplies recommended.

HART is compatible with I.S. rules and HARTcommunicates across most I.S. barriers.

Zener diode barriers work with HART (Theynormally allow two-way communications).

Isolating barriers must be HART compatible(i.e., some isolating barriers support one-waycommunication only).

n Network setup simple andcompatible with standard4-20mA wiring practices

n Many instrument types andnetwork topologies allowed

Control

System

"Two-Wire"Transmitter

Loop-PoweredValve/Actuator

"Three-Wire"

Transmitter

+24VDC

+24VDC

CurrentSense

Resistor

HandHeld

Multi-Drop

Loop


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Other Network Topologies

n Like a Single Loop Controller

n 4-20mA Signal drives the loop PID in transmitter

4-20mA is Control Signal

PID in actuator4-20mA is Process Signal

n HART used to monitor andprovide supervisory control

n Leverages both HART's twocommunication channels

n Normal 4-20mA Signaling

n HART Access to both valves Re-ranging

Adjusting Valve Action

Monitor Both Valves' actual

position

Closed LoopClosed Loop

(e.g., PID) Contro l(e.g., PID) Contro l

Spl i tSpli t--RangingRangingValvesValves

+24VDC

ControlSystem


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The HART Data Link Layer

n Converts Physical Layer Signals into Data All HART data is grouped into 8-Bit Bytes

n Organizes the Data in to Message Frames HART Messages or Frames Consist of Delimiter, Address, [Expansion,]

Command, Byte Count, [Data,] and Check Byte Fields

n Uses Addresses to Ensure Delivery to the Correct Network Device

HART Masters have a 1-Bit Address HART Slaves have a 4-Bit and a 38-Bit Address

n Provides Error Detection and Management HART uses a "Single Parity Check Product (SPCP) Code" i.e.

Odd Parity on Each Byte and

A Check Byte at the End of the Message

n Controls Device Access to the Media HART is Token-Passing with Each Message Implying the Passing of a

Token to Another Device

Objectiv e: Reliable Transpo rt of DataObjectiv e: Reliable Transpo rt of Data

Ac ross th e Physical LayerAc ross th e Physical Layer


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Example Transaction

n Half Duplex - Only One Device Talks at a Time

n Analog Signaling of Digital Data - Receiver must Synchronize to the Incoming Analog Signals

n Sequence: Carrier Ramps Up

Preamble Syncronizes Physical Layer (Demodulator and Receiver) Message Tranferred

Carrier Ramps Down

Repeat for Slave Reply

Master Request

MessagePreamble MessagePreamble

Slave Response


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The HART Message Packet

n Delimiter- First byte of the message.Tells message framer where the ByteCount is. Indicates the Message Type.

n Address - Indicates the master andslave conversing. 5 bytes long, uniqueaddress. Indicates the master andslave communicating

n Expansion - 0-3 bytes reserved forprotocol enhancements.

Delimiter Byte Count Check ByteCommand [ Data ]Byte Count[Expansion]Address

n Command - Tells the ApplicationLayer what information is beingtransferred or action beingperformed.

n Byte Count - Tells message framerwhere the Check Byte is and theApplication Layer how muchinformation is being transferred.

n Data - The message "Payload".

n Check Byte - An XOR of all messagebytes starting with the Delimiter.


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Communication Reliability

nPhysical Layer Worst case 1 Bit Error in 10,000 (BER 104)

(Very Noisy Wire)

Most applications BER >> 106

nData Link Layer Simple to implement, very robust Error Detection

Parity on each byte

Check Byte on whole message

Probability of undetected error:

Less than 1 in 200 years

nMore Reliability Features Unique Addresses = Right Field Device gets the message

Few Delimiters (Start Byte) = Message is Framed Right

Application Layer has even more checks.


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Accessing a HART Network

n Implied Token Passing Relatively Simple to implement

Each message indicates who talks next

Masters and Burst-Mode Slave taketurns sharing the network

Not all Actors need be present

Timers control token recoveryn Most Networks a 4-20mA loop

with a single HART Field Device Usually Silent until Master Talks

n The Players:

SecondaryMaster

Slave

Burst ModeSlave

Primary Master(e.g. a Controller)Monitor / Recorder

(Passive)

Actor Qty DescriptionPrimary

Master

0-1 Can Initiate a transaction. Has access to

the network before the Secondary Master

SecondaryMaster

0-1 Can Initiate a transaction. Same access rules asPrimary (only one timer value is different)

Slave 1-n Only responds to Master requests

Burst ModeSlave

0-1 Publishes Process Data; Responds to masterrequests; PLUS (if present) controls network access.

Monitor 0-n Listens to the network (e.g., captures process datapublished by burst mode slave)


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Request

Response

Two Types of Transactions

Request / Response( "Master / Slave" )

n Slave device only communicateswhen requested

n Responds to Master Commandn "Grant Time" used to allow

access by other Master

n 2-3 Transactions per Second

Burst Mode

(Publishing Process Data)

n Optional Slave Support (> 65%)

n Slave continuously transmitsselected command response Only Process Data Commands

(i.e., 1, 2, 3, 9, 33) may be burst.

n "Grant Time" used to allowaccess by designated Master Master performs usual Request /

Response Transaction

n 3-4 Transactions per Second

Slave PublishesDigital Process Data


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HART Network Access Rules

n Network operates in one of two modes: "Normal" mode: master gets token implied by

slave response other master Master recovers lost token using timers

"Burst" mode: master gets token implied byburst message to other master

Burst mode slave recovers token

n Masters must wait afterConnecting to the Network Ensures no collisions

"Synchronizes" Master

Then master can issue aslave request message

Master stays Synchronizedas long as Connected

1. The master connects to the channel.

2. After the "Link Quiet" timeout the master becomessynchronized to the channel.

3. Master obtains the token when: (A) the timer expires; or(B) a token pass implied by the message on the network

4. Once the master has the token and must begin a

transmission with the "Hold" time.5. Once the message is sent, the slave is required to begin

its response within Slave Time Out".

6. The slave transmits a reply and the master starts the"Link Grant" timer.

7. If there is no other master then the "Link Grant" timerexpires.

8. The master must begin another transmission(i.e., go to step 4)

Typical Master Communicat ion SequenceTypical Master Communicat ion Sequence


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HARTCopyright - HART Communication Foundation, 2002Page 25 of 59

The HART Application Layer

n Mission: Correct Exchange of Information Data Link Layer: Error-free transport of data

Application Layer: Does the data make sense?

Response Codes Indicate Correctness of master request

n

Specifies HART data types Classes of commands:

Universal Commands

Common Practice Commands

Device Family Commands (Extention to Common Practice)

Device Specific Commands

Standard Device and Process Data Status

Standard Operating Procedures (e.g., Re-ranging, Calibration)

Delimiter Byte Count Check ByteCommand [ Data ]Byte Count[Expansion]Address

10 Protocol Specif icat ions are App l icat ion Layer10 Protocol Specif icat ions are App l icat ion Layer


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Some HART CommandsUniversal Commands Common-Practice Commands

Cmd Description Cmd Description

0 Read Unique Identifier Uses the "polling address" to establish a connectionwith the field device.

34 Write Primary Variable Damping Value

1 Read Primary Variable 35 Write Primary Variable Range Values Changes primary process variablevalues used as the 4 and 20ma operating points

2 Read Loop Current And Percent Of Range 38 Reset Configuration Changed Flag

3 Read Dynamic Variables And Loop Current Reads the loop current, PV and(if device is multi-variable) SV, TV, QV

40 Enter/Exit Fixed Current Mode Allows the loop current value to be forced.Used in Loop test and calibrating the loop current (see Commands 45, 46)

6 Write Polling Address 41 Perform Self Test

7 Read Loop Configuration Reads the polling address and whether the loopcurrent is active or not.

42 Perform Device Reset The device perform a hard reset (i.e., the same effectas cycling the power on and off).

8 Read Dynamic Variable Classifications Reads the type of each processvariable (pressure, temperature,. mag-flow, etc.)

44 Write Primary Variable Units

9 Read Device Variables with Status Reads up to 4 process variables withdata quality status.

45 Trim Loop Current Zero Adjusts the loop current to 4ma. Does not affect therange values or the digital primary process value

11 Read Unique Identifier Associated with Tag. Uses the 8-character tag toestablish a connection with the field device

46 Trim Loop Current Gain Adjusts the loop current to20ma. Does not affect therange values or the digital primary process value

12 Read Message

13 Read Tag, Descriptor, Date

14 Read Primary Variable Transducer Information

15 Read Device Information Reads upper and lower range values and otherdevice related

16 Read Final Assembly Number

17 Write Message

18 Write Tag, Descriptor, Date

19 Write Final Assembly Number

20 Read Long Tag

21 Read Unique Identifier Associated with Long Tag Uses the 32-character tagto establish a connection with the field device

22 Write Long Tag

Note:

1. All devices must support all UniversalCommands.

2. There are many Common Practice Commands.However, the ones listed are commonly usedin the vast majority of devices including eventhe simplest devices available.

3. Commands 0, 11, 21 are three of the IdentityCommands. All return the same identity data


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Valuable Data - Simple to Support

n 35-40 data items Standard inevery HART device Device Identification

Basic Calibration data

Process Variables - bothmeasured and calculated

Diagnostic Alerts

n All Data is easily accessedby HART-enabled Systems

DD's Not Required Accessed the same way in all

HART compatible devices

n This data is valuable toImprove Operations andManage Plant Assets


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Digital Process Variables

n Many HART devices are Multi-Variablewith more than one processmeasurement or calculated value

n HART communication provides accessto All Process Variables in the device

n Digital Process Variable data includes:

IEEE Floating Point Value

Engineering Units Code

Data Quality Assessment

n The Primary Variable is transmitted onthe 4-20mA current loop continuously,

but it can also be read as a digital value


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Status & Diagnostic Alertsn

All HART smart field devices continuously self-assess and monitor their performance

n Diagnostic status information is returned withevery message

n Alerts include problems with 4-20mA signaland process variables out of limits

n

Continuous communication with field deviceincreases the integrity of control & safetysystems

Real-time diagnostic alerts provide earlywarning to problems

Detect any miss-match in calibrated Rangeor Engineering Units between device andsystem

Secure 4-20mA communication channel toensure accurate transfer of controlinformation


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SPA uses HART communication to get process variable anddiagnostic data from device and converts information into 4-20mA signals and/or contact closures

HART Instrument Fault Alarm

Second Variable (SV) High/Low Alarm

Third Variable (TV) High/Low Alarm

Fourth Variable (FV) High/Low Alarm

3 ea 4-20mA Loops Proportional to SV, TV, or FV

4-20mA Proportional to PV

One Wire from Field to Con trol Room

Mult ip le Analog Signals and A larm Contacts to the Contro l System

Easy to Use in Even Simple Hosts


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HART Dig ital In tegrat ionHART Digital In tegrat ion

Benefits of Full Time HART Communication


32/59



Today What Cou ld Be

Consider the Possibilities

n Millions of HART CompatibleField Devices Already in Plants

n Most installed Systems Don'tSupport HART

n Only 4-20mA Used Continuously

n Good Value Provided Improve Technician Efficiency

Minimize Maintenance Stores

n Existing HART System SupportLargely Token Intermittent, Pass-Through HART

Communications

Focus on Maintenance and

"Asset Management" HART Used in Reaction to a

Problem

Multiplexed I/O Limits Utilizationof HART Field Devices

n Full-Time HART Communication

n Smart I/O Systems Validate High-Speed 4-20mA

Communication Channel

Support Reporting by Exception

Full Access to Multi-Variable Devices

n Control Utilize HART Digital Data

Understand HART Status

Standardized HART Templates

n Benefits Validated Process Data - Improved

Product Quality

Reduced I/O Count - 1 Channel perMulti-Variable Field Device

Early Problem Detection - PreventUnscheduled Downtime

Lower Maintenance Costs - FewerUnnecessary Service Calls

Improved System Integrity


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All HART Devices Hold aReal-Time Data Base

n All HART Field Devices Continuously UpdateTheir Real-Time Database 24/7 You Already Own The HART Devices

You can Only Get All the Data by ContinuousHART Communications

n HART Instrument is RTU in SCADA System A Different Way of Thinking

n How does this Fit into System View of anEnterprise?


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A System as a Distributed Real-TimeDatabase Applicationn Many R-T Databases scattered

throughout the System

n Field Device Closest to Process Its DB Reflect Process Conditions

The Rest of System Needs Accessto ALL of this Data

n Other System Components Have DB with Pieces of Many Field

Device Databases

Their Copy of the Data must be Current,Accurate, Reliable

n The Field Device is Part of the System Not All Control Systems Think This Way

Similar to SCADA Thinking

n HART's Huge Installed BaseAlready Supports This System View! HART is How The DB in the Decision

Makers is Kept in Sync With the Process

Remote I/O

Enterprise Networks

Field Controller

MaintenanceStation

Operator Stations

Plant Network

Data Historian

MIS/ERP

SPC/SQC

SCADA

HART FieldDevices


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Field Communications - The Critical Link

n Reliable, Continuous Communication isCritical to Making Good Decisions

n 4-20mA Only Support Produces an"Information Gap"

n With Many Systems Only 4-20mACommunication is Continuous Real-Time

Only a One Data Item Is Communicated Communications is limited to One Direction

Secondary Process Variables, Data Quality,and Real-time Diagnotics . . . Lost.

n Communications is Not Secure Distortion in 4-20mA May Not Be Detected

Meaning of 4-20mA Signal Can Change Erroneous information if 4-20mA set-up indevice and system not aligned

Cont inuou s HART CommunicationCloses the Info rmat ion Gap

Without HARTWi thout HARTThere is a GAPThere is a GAP

44--20mA Pipe Open20mA Pipe Open

HART Pipe ClosedHART Pipe Closed

Cont ro lCont ro l

NetworkNetwork


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An Integrated HART Systemvs. 4-20mA Only

n

Highest possible communication ratefor a Single Process Value

n 4-20mA control signal must be manuallyverified Calibration of field device and I/O

channel

Matching Range for both I/O and device

n Highest possible communication ratefor a Single Process Value

n HART Communication closes theInformation Gap Secures integrity of 4-20mA signal

System can validate accuracy of the 4-20mA signal and continuously monitordevice diagnostics in real-time

Enables access to additional informationin multi-variable devices

HART Digital

Communicat ions

4-20mA Commu nicat ions

HART Devices Have TwoCommunicat ion Channels


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4-20mA Signal Validation

n 4-20mA signal from field device maydiffer from the 4-20mA received at thesystem Erroneous control signal produced by

unexpected external influence

Detectable ONLY if signal out of range-above 20mA or below 4mA

n 4-20mA signal validated continuously

n System automatically detects anydisagreement between Field Device andI/O I/O continuously checks loop current for

agreement with digital values from device Continuous communication detects any

device or process connection problems

Automatic calibration of the 4-20mApossible


HART Pass-through Won 't"Get the Job Done"

Loop fault

HART Digital

Communicat ions


38/59



Field Device Problem Detection

n Only Catastrophic Failures Detected 4-20mA signal must be outside normal

operating range to detect problem

Non-catastrophic failure may cause error in4-20mA signal - temp compensation loss

n Disruption to Process Operation Likely

Unscheduled downtime or impact toproduct quality

n Real-time Diagnostic Alerts from Device Extensive self diagnostics - "Device Needs

Maintenance", "Valve Not Tracking SP"

Change in Device Status

Supports "Self Validating" Devices

n Process Disruption may be Avoided Operators alerted to problem early

Enables pro-active action for minimumimpact to process operation


Field DeviceFailure

HART Digital

Communicat ions


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Process Overload Condition

n Loop Current saturated (e.g. at 3.8 or20.8mA) or frozen (fixed) I/O is "Blind - No usable Process Value

Process measurement may simply beOut of Range

n Manual Inspection Necessary to

Diagnose the Problem

n Process Measurement still availablewith HART Communication I/O can still "See and provide

information for operator display

n Diagnostic Alerts indicate data quality "PV out of Limit", "Secondary Variable

Out of Limit", "Loop Current Saturated"

Diagnosis possible without costly trip tothe field


TransducerOverload

HART Digital

Communicat ions


40/59



Change in Field Device Configuration

n Change to 4-20mA signal may NOT beapparent

n Change in operation may NOT bedetected

n Status alerts flag any change toparameters "Configuration Changed" flag

"Configuration Change Counter

Any configuration change detectedimmediately

n Supports Multiple Masters and LocalPanels "Lock Device" Command to prevent

another Master or Local Panel frommaking changes


Range Change viaLocal Operator Panel

HART Digital

Communicat ions


41/59



Seven Commands forDigital Integaration of HART

n Read the Loop Current Command 2

Does the loop current in theI/O match the Field Device's?

n Read the Process Variables Command 3, 9, or 33

Access to SecondaryVariables in Field Device

Validates Primary Variablesent using the loop current

n Detect Status Change Status in Device Response

Plus any change inCommand 48 Data

Trigggers notification ofOperator

n Check the Range Value Command 15

Has the meaning of the loopcurrent changed?

n Test and Calibration the LoopCurrent Loop Test with Command 40

Calibrate (if needed) withCommands 45, 46

Analog CommunicationChannel Integrity

n Detect Change in Instrument

Configuration Status in Device Response

(Configuration Changed bit)

Command 0 (change counter)

Trigggers notification ofOperator


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HART Digital Integration -Throughout the System

n

One-One Smart I/O Ensure Reliable Field Communication High-Speed 4-20mA Comms Validate Using HART Best to detect 4-20mA Errors

Analog and Digitital Data Acquisition 4-20mA Primary Process Variable (Convert Using

HART Range Values) HART for Secondary Process Variables, Data Quality

and Status

Reporting by Exceptionn Field Controller

Utilization of HART Multi-Variable Devices Easy Access to and Use of All HART Process Data

And Status Apply Full Knowledge of Process For Optimization

and Control

n Operator Station

HART Allows Full Window into the Process Early Notification of Potential Problems

n Maintenance Station Detailed Instrument Configuration DB Only one that Needs More than Standard HART

Data and Commands

You Own The HART Devices -Use The Data


43/59

Understand ing Systems

Implementat ions

Understand ing Sys tems

Implementat ions


44/59



0 Host does not meet the minimum requirements of Conformance Class 1

1 The host can utilize cyclical process data from any field device

2 The host can supply the user with basic identification and configuration data

from any field device

3 The host can perform basic configuration for any field device - Minimum

level for classification as Generic Host

4 The host provides basic commissioning and calibration support for any device

5 The host can access all data items and device specific functions for any device

Class Description

Capabilities of HART Hosts

n

The application and implementation affect system capabilities Pass-Through - HART Commands can be communicated but, thecomponent itself may directly Use / Support HART Capabilites

Multiplexed I/O - One HART Communication Channel Shared Betweenmany Device Connections. Resulting Communication Painfully Slow.

n Simple HART features not supported in all Masters

n

HART Protocol Specifies Master Classifications Helps Understand HART Capabilities Supported Starting Point for a System Discussion.


45/59



I/O System Considerations

n HART Data Link Layer Token Passing Supports Multiple Masters

Synchronization Time Required WhenConnecting to a Channel

n One-One, Buffered I/O One Modem - One Network

Buffered to Avoid Lost Tokens

Supports Burst Mode Publishes Cyclic Data

Even Faster Process Data Updates

Best Access to HART device DB

n Multiplexed I/O Shares 1 HART Comm Channel

With Many Networks

Many Times Slower Than Pointto Point Communications

Slower Than HART MultiDrop

Limits Utilization of Field Device

NumberChannels

One-One Point-Point(unbuffered)

Multi-Drop Multiplexed

1 0.38 1.16 0.38 0.38

4 0.38 1.16 1.51 2.80

8 0.38 1.16 3.02 5.60

16 0.38 1.16 6.04 11.21

32 0.38 1.16 12.08 22.43

256 0.38 1.16 --- 179.42

NumberChannels

One-One Point-Point(unbuffered)

Multi-Drop Multiplexed

1 2.65 1.14 2.65 1.43

4 10.60 4.56 2.65 1.43

8 21.19 9.12 2.65 1.43

16 42.38 18.24 2.65 1.43

32 84.77 36.48 2.65 1.43

256 678.13 291.84 -- 1.43

Latency(seconds)

Throughput(Transact ions Per Second )

I/O System Perform ance

Be Aware of I/O System Throughp utand Latency Stat ist ics


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Multiplexed I/O WithMulti-Variable Field Devices

n Multiplexed I/O Slows HART Access 5-6 Second (8-Channel Mux) Or More Latency

Limits Use of HART Data

n Multi-Variable Digital Data Access Slow May Require Adapter for Faster Secondary Variables

HART Burst Mode Converted to 4-20mA Degraded Accuracy / Security

HART Communications Sets 4-20mA Update Rate

Wasted I/O Channels More Hardware and Complexity

n True Continuous HART Communication 0.5 Second Latency

Full Access to All Field Device Information

Closes the Information Gap

4-20mA Communcation Security Enhancedn Multi-Variable Digital Data Access Practical

Secure Digital Process Data with Status

Saves I/O

n The Reliable, Simple System

One-One I/O

Multip lexed I/O

Cont inuous HART Comm unicat ion not Pract ical

Maximizes Return o n Investm ent

Tri-Loop

or HIM

Multi-VariableField Devices

4-20mA

4-20mA + HART

Multi-VariableField Devices

4-20mA + HART


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HARTHARTDataData

The Maintenance Station "Add-On"

n

Easiest Way to Add HART Support to aConventional Analog System Usually Uses "Multiplexers"

Duplicates Existing Hardwareand Wiring

Maintenance Station Primary Recipient

n

HART Data Access Slow HART Communications Limited Access to HART Data

Maintenance Station May Publish Data(e.g., using OPC)

Operator Station

Data Historian

No HART Access in I/O System, Controller

n Benefits Remote Diagnostics / Maintenance

Lowers Maintenance Costs


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HARTHARTDataData

HART Pass-Through

n 1st Generation System Support Communication not Continuous

Usually Uses Dumb Multiplexed I/O

Maintenance Station Primary Recipient

n HART Data Access Very Slow Communications

Limited Access to HART Data Little Native HART Knowledge in I/O

Controller HART Data Access Possible(Can be Difficult to Achieve)

n 4-20mA Communications Not Secure I/O Knows 4-20mA Value

Not the Maintenance Stationn Benefits

Remote Diagnostics / Maintenance

Lowers Maintenance Costs

Reduces Hardware and Wiring Duplication


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Systems withIntegrated HARTAbility

n

Support True Full-Time HART Communications Enhances Early Problem Detection - Reduces Unscheduled Downtime Lowers Maintenance Costs - Fewer Unnecessary Service Calls

Validates Process Data - Improves Product Quality

Improves System Integrity

n These Systems Contain Smart One-One I/O Systems

Continuous Validation of 4-20mA Communication

Real-Time Access to Digital Secondary Variables -Exploit Your Multi-Variable Field Device Investment

Simplifed, Cost Effective I/O - One Channel per Multi-Variable Field Device

Monitor HART Status - Enables Reporting by Exception

HART Aware Controls Utilization of HART Digital Process Data and Data Quality

Standrd Templates to Simplify Acces to HART Data and Status

Full Access to All HART Data = Full Knowledge of the Process

Operators Station with a Complete View into the Process


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Solutions for HART Integration


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I/OI/O

ControlControl

HMIHMIEngineeringEngineering

MaintenanceMaintenance

HH

AA

RR

TTDD

AA

TTAA

HART System Integration

n Cost-effective interface solutionssupport integration with plant controlsystems

n Many control systems have directHART-capable I/O and support use ofthe data at all levels

n Third party products supportintegration with legacy systems Multiplexers - Some integral with Field

Termination Assemblies

Gateways - HART to Ethernet, HART toModbus, HART to Profibus, more

Single Device Interfaces - convertdigital process variables and devicediagnostic alerts into 4-20mA signalsand/or contact closures


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HART SERVERTOOL

Integration with Plant Networks

n OPC Server provides easyaccess to HART device dataanywhere on plant network

n Allows several applications toaccess data in a HART device atthe same time

n Enables popular HMI andTrending packages to accessdata in HART devices

n Connect to one or thousands ofdevices using common HART I/Osystems & interfaces

n HART Data on Your Desktopanywhere in the plant


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High VALUE + LOW Risk

HART Integration Summary

n

Continuous Real Time Diagnostics Device Problems Loop Current Faults

Device Needs Maintenance

n Continuously Validate Integrityof Control Information

Ensure accuracy of system data Verify Loop Current, PV and

Range values in device matchthose of system

Automatically detect any deviationbetween device and system

n Unlock additional information in Multi-Variable devices Secondary Process Variables for operator display, trending, or control

Better information to improve plant operation and manage assets


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Unleash the Power

n

Pick What Benefits Make Sense For Your Plant Value Today with Little or No Integration(Just Using a Handheld)

Benefits Grow as Your HART Integration Grows

n Major Plant Overhaul Not Required HART Compatible with existing instrumentation

systems and people

Allows benefits to be achieved incrementally

Use Your Field Devices Better,Don't Throw Them Away and Start Over

n Migrate at Your Pace Focus on Key Process Units

Strategically Enahance Your System Get More From the HART Equipment You Already Own

Add Smart I/O, HART Aware Control, Asset ManagementTools, More HART Field Devices

Evolution Not Revolution

n Low Risk, Cost Effective, Excellent ROI


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Take Action!

n Learn More About HART Provide HART capability training for your staff

Understand the Opportunities Which Capabilities Fit Your Plant Needs

Which Tools Deliver those Capabilited

n Ask Lots of Questions - Like What Conformance Class Level Is Its HARTability?

Is The I/O Smart? Can it Validate and Secure the 4-20mA Communication?

Is it only capable of Pass Through?

Is it One-One or Multiplexed?

How does it Support Multi-Variable Field Devices?

Is the Control HART Aware? Does it Make it Easy to Use all HART Capabilities?

Can it use the Secondary HART Digital Processs Variables?

Does it Understand the HART Status

Can it Detect Configuration Changes

Keep Asking Questions

n Be Pragmatic and Start Evolving Your Systems


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HARTCOMMUNICATION FOUNDATION

Support for HART Technology

n Provide Worldwide Support for Application of theHART Communication Technology

n Technology Owner and Standards Setting Bodyfor HART Communication

n Independent Non-Profit Organization - Funded byMembership and Training/Support service fees

n Any Company interested in Use of the HARTProtocol should be a member


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Foundation Services

nManage and control the HARTCommunication Protocol Standards

nEnhance the HART technology asnecessary to support industry needsfor Smart Instrumentation

nProvide Training Workshops,

Newsletters, Web Site and otherServices to Educate Industry on useof the HART Protocol

nManage Library and distribution ofRegistered Device Descriptions for allHART devices


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The Bottom Line...

Most Users and Suppliers are not usingthe fullvalue of HART

Communicate with your HART devicesand...

Unleash the POWER!


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HARTC Cf

Questions?

Wally PrattHART Communication Foundation

9390 Research Blvd., Suite I-350

Austin, Texas 78759 USA

Tel: 512-794-0369

Fax: 512-794-3904e-mail: [email protected]

www.hartcomm.org

Thank You for Your Attention!

Documents

Basics of Hart