HART Commands - Ifea

HART 

Technology Overview 

September 19, 2012

HART Topics 

Hart Basics 

Hart Communication 

Hart Benefits 

Hart Usage in DCS 

2 HONEYWELL September 19, 2012

The HART Message 

HART is: 

� Simple! 

� Easy! 

� Inexpensive! 

� Feature Rich! 

Some Additional Benefits: 

For: 

� The HART Device Vendor 

� The Control System Vendor 

� The End User 

+ Ability to select from a wide range of device types and manufacturers! 

+ A very large installed base! 

3 HONEYWELL September 19, 2012 

3

HART Foundation Registered Devices 

There are over (990) devices from (238) different device vendors: 

Including the following device types: 

• Pressure 

• Flow 

• Level 

• Density 

• Temperature 

• Analyzers 

• Analytical devices 

• Positioners 

See WWW.hartcomm.ORG for the latest product listings 

4 HONEYWELL 4 

September 19, 2012

HART Device Information 

4-20 mA Analog Signal: 

The primary control signal is a standard 4-20 mA (0-100%) signal. 

HART Digital Data: 

In addition to the 4-20 mA signal, each HART field device maintains a 

database of information. 

Major data types maintained in device memory: 

� Device ID information (Tag, manufacturer, model, SN, etc.) 

� Software and hardware revision level 

� Dynamic variables (PV, SV, TV, and FV) 

� Device variables (Slot-0, Slot-1, Slot-2, and Slot-3) 

� General and device-specific status information 

� Range related information 

� Full device setup and configuration information 

� Trends and test analysis data 

Notice! 

You must check with each HART device vendor to determine what data is 

available in a given device type and revision. 


5

DD-POP Tool and HART Device Templates 

Honeywell: 

DD for: 

ST3000 transmitter 

Version 0202 

Experion PKS: 

HART DD-POP Tool 

Device Template: 

ST3000_0202 

Now appears as a selection in 

Control Builder. 

There must be a match between the actual Transmitter (Device) Revision 

number and the first two digits of DD revision number! 

Example: 

If the Transmitter (Device) revision = 02 

Then this xmtr can be used with any DD that begins with an 02 (DD 02xx, the 

xx number does not matter) 


6

HART Communication Protocol Features 

HART Version 

Feature 7 6 5 

Analog Loop Check � � � 

Broadcast Message � � � 

Device Calibration � � � 

Device Configuration � � � 

Device Status � � � 

Multi-Variable Reads � � � 

PV with Status � � � 

32 Character Tag � � 

All Variables with Status � � 

Digital Loop Check � � 

Enhanced Multi-Variable Support � � 

Local Interface Lock � � 

Manual ID of Device by Host � � 

Peer-to-peer Messages � � 

Visual ID of Device � � 

Time or Condition-based Alerts � 

Report by Exception � 

Synchronized Sampling � 

Time Stamp � 

Trends � 

Wireless Co-existance � 

Wireless Diagnostics � 

Wireless Mesh and Star Topologies � 

Wireless Message Routing � 

Wireless Security � 

HART 7 – Key Features 

• Enhanced Data Publishing 

- Support for Publish by Exception 

- Automatic Event Notification 

• Time Stamped Data 

- Know when the measurement was made. 

- Improves signal processing and control 

• Time-triggered Actions, 

Measurements 

- Measurements or actions can be triggered at 

specified time 

- Allows synchronized operation across multiple 

devices 

• Process Variable Trends 

- Multiple sequential data points of same process 

variable in one packet. 

• Command Aggregation 

- Multiple read commands in one transaction for 

faster configuration uploads 

• WirelessHART 

- Added feature to HART 7 


Smart Field Devices Enhanced Sys. Integration 

Autonomous Process Solutions


Hart Basics 


Hart Benefits 



HART Device Analog Signal 

HART Output Device: 

Examples: 

• Valve Positioner 

• Drive 

• Etc. 

HART Input Device: 

Examples: 

• Flow transmitter 

• Level transmitter 

• Temperature transmitter 

• Analytical device 

• Etc. 

4-20 mA 

24 Vdc 

4-20 mA 

4-20 mA (0-100%) 

analog signal is 

generated by the 

control system and 

is used to drive the 

field device. 

4-20 mA (0-100%) 

analog signal is 

generated by the 

field device. 

9 HONEYWELL 9 

September 19, 2012 

AO 

I 

O 

M 

AI 

I 

O 

M

HART Device Digital Signal 

HART Input Device: 

HART Output Device: 

24 Vdc 

4-20 mA 

4-20 mA 

The HART digital signal is superimposed on 

the standard 4-20 mA signal. 

All memory resident device data is 

accessed using the HART digital protocol. 

+0.5 mA 

- 0.5 mA 

1200 

Hz 

“1” 

2200 

Hz 

“0” 

10 HONEYWELL 10 


FSK

HART Communications 

20 mA - 

Analog 

Signal 

4 mA - 

Time 

C 

+0.5 mA 

- 0.5 mA 

The control signal (PV/OP) is transmitted using a 

traditional analog 4-20 mA (0-100%) signal. 

R 

C 

R 

FSK 

C 

1200 

Hz 

“1” 

C- command R- response 

2200 

Hz 

“0” 

HART digital data is 

transmitted using the 

HART digital protocol. 

Half-duplex Command- 

Response. 


R 

C 

11

HART Digital Data Frames 

20 mA- 

4 mA- 

Command (From Master) 

Preamble Start 

Character 

Response (from Device) 

Preamble Start 

Character 

Device 

Address 

0-15 

Device 

Address 

0-15 

• 4-20 mA is available in real time! 

[1]- Command from Master 

Command 

No. 

(0 - 253) 

Command 

No. 

same as CMD 

• HART Digital Data is CMD/Response (Half-Duplex) 

[2]- Device time required to respond……... 

[3]- Response from Device 

Byte Count in 

this transaction 

0-25 

Byte Count in 

this transaction 

0-25 

Data in 

Command 

Status 

2-bytes 

Checksum 

Data 

in 

Reply 


12 

HART Device 

Read data, Write data, or command Device to perform an action. 

Checksum

HART Commands 

• Universal Commands (0-30): 

– Represents the basic command set required by most HART devices. 

– All commands in this set must be supported by all HART devices. 

– Commands must be implemented exactly as specified by the HART foundation specification. 

– DD interpretation is not required for this command set. 

• Common Practice Commands (32-121): 

– A set of commands applicable to a wide range of devices. 

– This command set should be supported by devices whenever possible, but it is not mandatory. 

– Although the function of each command is well defined by the HART foundation specification, 

the actual meaning of the response data may require the interpretation of vendor DD files. 

• Device-Specific Commands (128-253): 

– This Command set is completely defined by the device vendor. 

– Each command performs a function that is specific to the particular device type and model. 

– The use of these commands requires full interpretation of the vendor DD files. 

DD -Device Descriptor file 

Demo Command-3 

Demo Command-48 


13


Hart Basics 


Hart Benefits 



Where is the value for the customer? 

• Detailed device performance and status information. 

Customers are asking device vendors to implement more predictive type algorithms in the 

field device. 

• On-line configuration tweaking (i.e. damping and range) 

• Absolute (not inferred) information about each device. 

• Reduced time in startup and commission phases. 

• Remote HART device configuration and setup. 

• Remote HART device configuration verification. 

• Quick and validated re-configuration for turn around and product changes. 

• Reduced cost in wiring with access to secondary variable information. 


September 19, 2012


Hart Basics 


Hart Benefits 



HART Modem Interface 

HART device 

Configuration 

Database 

Honeywell 

FDM 

(Server) 

FDM allows the user to configure 

a device on the bench (locally) 

using the HART Modem 

interface. 

RS-232 HART protocol 


Modem 


Hardware MUX Connection 


Hardware MUX Connection 


Configuration 

Database 

Honeywell 

FDCM 

(Server) 

RS-232 

By adding additional 

terminal panels and 

modems, the user can 

access up to 7936 HART 

devices per one Hardware 

MUX. 

RS-485 


Hart Enabled IO 

Eg. Experion PKS Interface 

C200 

EtherNet 

EPKS 

Server 

C300 

PMIO CIOM-A Series C 


Configuration 

Database 

Honeywell 

FDM 

(Server) 

FDM can access all device 

information directly through the 

HART AI and AO cards. 

No additional communication 

hardware or software is required! 

Up to 10,240 devices / EPKS Server 


Wireless Hart Adapter 

WDM 

XYR6000 

Transmitters 

Plant Network 

FDAP 

HART Transmitter 

with OWA 100 

OneWireless 

(Any PC with Web 

browser) 

XYR6000 

Transmitters 

FDM or AMS 

System 


Transmitter 

with OWA 100 

• OWA 100 sends/receives HART PV data & 

commands wrapped in ISA100.11a Wireless 

Protocol 

• Brings HART PV (4 PV’s) & Status information 

back to WDM via FDAP 

• WDM presents data to backhaul so it can be seen 

by FDM or AMS system 

• FDM or AMS thinks it is connected to a HART 

device, OneWireless sees it as an ISA100.11a 

Device, both can see the data 

• Configure HART device from FDM or AMS over 

the wireless network 

• OWA 100 can be Routing device or non-Routing 

device 

• Works with most any HART device, can be wired 

or wireless 


Wireless Adapter 

• Eg. The OWA 100 Adapter 

- Adapter takes HART information and 

transmits using the ISA100.11a protocol 

- Mounts to a HART device 

- Sends and receives HART information and 

commands 

• Installs on 2 wire, 4 wire or Wireless 

HART devices 

• Part of the Honeywell R200 

OneWireless Network 

• Seamlessly integrated into Experion 

Orion 


FDAP 

FDM – HART Communication Options 

Transmitters 

with OWA’s 

Experion Server 

FTE 

WDM 

C200 

Experion 

RCI 

FDM 

Server 

FDM RCI 


Modem 

MTL 

MTL 

MTL 

MTL 

MTL 

Fiber optic 

Converter 


Multiplexer 

REMOTE 

Experion Station or 

FDM Client or Stand alone PC 

Safety 

PLC 

FTA (Field 

Termination 

Assembly) 

MTL 

MTL 

MTL 

MTL 

MTL 

MTL 

MTL 

MTL 


Modem 

Fiber optic 

Converter 

Experion Station 

and/or 

FDM Client 

Or 

Stand alone 

PC 

Fiber optic 

Converter 

MTL 

MTL 

MTL 

MTL 

MTL 

MTL 

MTL 

MTL 

This Remote 

Communication Interface is 

included in the base FDM 

server license 



Converter 

RS232- RS485 

Fiber optic 

Converter 

FDM RCI 

MTL 

MTL 

MTL 

MTL 

MTL 

Converter 

RS232- 

RS485 

FDM RCI 

FDM RCI 

FDM RCI 

Safety 

PLC 

FTA (Field 

Termination 

Assembly) 

Converter 

RS232- 

RS485 


Multiplexer 

MTL 

MTL 

MTL 

MTL 

MTL 


Modem 

REMOTE 

This Remote 

Communication Interface is 

an optional license

Design Criteria 

The control system and HMI must be 

designed to fully support and take 

advantage of these new smart device 

functions and features. 

AIM 

FT-1000a: 

• ID info 

• Range & Configuration 

• Device Status 

C-200 

Exp 

Exp 

Station 

Station Exp 

Station 

Exp 

Station 

Exp Server 

CM - FIC-1000 

AI-FB DACA PID AO-FB 

The smart field device is an intelligent 

entity that offers a new level of 

information and performance support. 

Smart devices require the control 

system to extend support beyond the 

IOM terminal screws to include the 

device in the field. 

Detail and Alarm Summary displays: 

- HART Device alarms and status are 

reported directly against the device Tag. 

- Each HART device has a dedicated 

detail display. 

FCV-1000a: 

• ID info 

• Range & Configuration 

• Device Status 


24 

AOM

HART IOM Implementation 


Input 

Device 


AI Module 

4-20 mA 

+ RTN 


AO Module 

+ - 

4-20 mA 

Both Modules: 


Output 

Device 

� Occupy one physical chassis slot position 

� Provide (8 or 16) HART I/O channels 

� Each channel can be configured as a 

standard analog only or HART enabled 

channel 

� Support point-to-point connections only 

(no multi-drop) 

� Can be placed into the Local and/or a 

remote I/O chassis 

� Count as one IOM in the total allowable 

per C-x00 maximum 

� Can be used in a redundant C-x00 

configuration 

� Support all of the usual 

certifications (FM, CE, etc.) 


25

HART Data- IOM Scanning and Data Cache 

1 

8 

Ch-0 

Ch-15 


AI 

Analog PV: (250 ms update) 

4-20 mA input is scanned, converted 

and published to the C-200. 

1 

8 

Ch-0 

Ch-15 


AO 

Analog OP: (25 ms update) 

0-100% value is received from the 

C-200 and then converted to the 

equivalent 4-20 mA value. 

The following HART device digital data can be cached on 

the AI and AO Module and will then available for use within 

the system: 

� Device ID information: (#) 

Tag, Manufacturer, Model, SW/HW Rev, SN, date, 

descriptor, Etc. 

� Dynamic variables: (+) 

Command 3 (PV, SV, TV, FV) 

� Device variables: (+) 

Command 33, Slot-0 through Slot-3 

� Range information: (#) 

Range Hi and Range Low 

� Device standard status: (+) 

General device condition, command and comm status 

� Device-Specific status: (*) 

Command 48, Device-Specific status 

(#) Scanned at start-up or loss of communication 

(+) Periodically scanned 

(*) Scanned whenever the device indicates an error 


September 19, 2012

IOM Cached Data Details 

The following HART data is accessed 

form the HART device and cached on 

the AI and AO IOM: 

Device ID information 

Dynamic variables 

Device variables 

Range information 

Device standard status 

Device-Specific status 

-Show details 

-Show details 

-Show details 

-Show details 

-Show details 

-Show details 


27

HART Periodic Data 

1 

16 

Ch-0 

Ch-15 


AI 

Analog PV: (250 ms update) 

1 

16 

Ch-0 

Ch-15 

Analog OP: (25 ms update) 


AO 

HART device variable scanning: 

Dynamic variables: (Cmd-3, PV, SV, TV, FV) 

Scanning configurable for every HART enabled channel! 

Update is configurable between 1 to 16 seconds for all 

sixteen channels exclusive of HART device induced delays. 

Device standard status: is collected every time cmd-3 is 

issued to a device. 

Device variables: (Cmd- 33, Slot-0 through Slot-3) 

Scanning configurable for every HART enabled channel! 

Update is configurable between 1 to 16 seconds for all 

sixteen channels exclusive of HART device induced delays. 

Note! 

Channels that are not enabled for HART and those 

that do not use command 3 or 33 (or at a low 

frequency) will allow other channels on the same 

IOM to scan Dynamic and Device variables 

proportionally faster. 


28

1 

1 

Non-cached HART Device Data 

16 

16 

Ch-0 

Ch-15 

HART AI 

HART Pass-through buffers 

Ch-0 

Ch-15 

HART AO 

All other non-cached HART data is serviced through the passthrough 

function. This function provides a service to handle: 

• Commands: 

- Universal 

- Common Practice 

- Device Specific 

Pass-through operation: 

• Methods: 

- Configuration related 

- Calibration related 

1. Accept a HART command from the Software MUX and 

store command in an open buffer. 

2. At next opportunity pass command to proper HART 

device. 

3. Wait for the device to respond. 

4. Send response back to the originator. 

IOM channel modes: 

Channel is in service: 

Pass-through is subservient to the collection of cached data. 

Channel is out of service: 

Pass-through is the primary function, cached data is no longer 

collected. 


29

Sample CM using HART 

The analog (4-20 mA) PV 

is accessed through a 

standard AI channel 

block 

IN(1) 

IOCHANNEL: AICHANNEL 

FI_1000A 

U1_TC (Channel-0) 

HART digital variables are accessed using 

connections with the HART Device Block 

FI-1000A.SV 

LOGIC: GT 

IN(2) 

COMPARE 

Deadband .5 

UTILITY: NUMERIC 

MAX_PV 

Numeric = 200 

PV 

LOGIC: ONDELAY 

DATAACQ: DATAACQ 


DELAY 

Delay Time 30 sec 

P1 

SI 

OP 

DACA 

PV 

REGCTL: PID 

Safe OP% = 0 

OP 

PV 

PIDA 

IOCHANNEL: AOCHANNEL 

30 

PVHI 

PVLO 

FCV-1000A 

U1_AO (Channel-0) 

The analog OP (4-20 mA) is handled 

through a standard AO channel block

IOM’s are Optimized for Control 

Ch-0 

Ch-15 

Ch-0 

Ch-15 

H 

Out 

H 

Out 

H 

Out 

H 

Out 

H 

Out 

H 

Out 

H 

Out 

H 

Out 

H 

H 

In 

In 

H 

In 

H 

In 

H 

In 

H 

In 

H 

In 

H 

In 

HART AO 

HART AI 

I/O 

Link 

Experion 

Server 

All the information needed for control 

is cached on the IOM and available to 

the control system and the user! 

� HART Device ID information 

� Dynamic variables 

� Device variables 

� Range information 

� General status 

� Device-specific status 


September 19, 2012

Configuration, Calibration, run Methods 

1 

8 

1 

8 

Read/Write 

1 

Handheld 475: 

- Configure 

- Calibrate 

- Run methods 


AI 


AO 

I/O Link 

C-x00 

Pass-through 

IOM acts as a bridge between 

the HART Device and the Software 

MUX. Pass-through is subservient to 

all other IOM tasks. 

Command restrictions: 

• Read anytime 

• None-volatile write anytime 

• Volatile writes when channel 

is in OOS mode only! 

HART Pass-through commands 

Supervisory Network 


Modem 

Local Bench 

Configuration/Calibration 

Experion 

Server 

- Configure 

- Calibrate 

- Run methods 



2 

Configure through the 

Field Device Manager. 

Field Device 

Manager Server

Plant Asset Management 

Asset Manager Server 

Asset Association: 

• Experion 

• Field Device 

• Process 

• Control Loops 

IO CNet 

Orient - Decide - Act - Improve 

Hardware centric View 

C-200 

Asset Manager 

DocuMint 

- Calibration services 

- Device Audit trail 

Supervisory CNet 

Experion 

server 

Ethernet 


ERDB 

RTDB 

Alarm/Event 

Rem RCI 

- PSc Configuration 

- Real Time Database 

Field Device Manager 

33 

- Alarms and events 

- HART Command 

pass-through 

- Configure HART devices 

- Run HART methods 

- Maintain Configuration History 

- Maintain Config/Method audit trail 

- Batch configuration function

www.honeywell.com 


The Dynamic variables 

(digital PV, SV, TV, FV) 

are accessed from the 

HART device using HART 

command-3 


September 19, 2012

HART Command-3 

Host (I/O module) 

Primary Variable 

Secondary Variable 

Note! 

The HART device vendor determines what 

variables are available for PV, SV, TV, QV! 

Third Variable 

Fourth Variable 

Command -3 

Data in response 

PV value (IEEE -754) & PV EU’s 

SV value (IEEE- 754) & SV EU’s 

TV value (IEEE- 754) & TV EU’s 

QV value (IEEE- 754) & QV EU’s 

2-Byte (16 bits) General Device Status 

Byte-1 Byte-2 

Examples: 

RETURN 

- Differential Pressure 

- Body temperature 

- High side static pressure 

- Low side static pressure 

General Device Status is always returned with command-3 data! 

- No device errors 



36

The general device status 

is returned along with 

command-3 

Dynamic variables 

(digital PV, SV, TV, FV) 


September 19, 2012

Communication Error 

AI 

AO 

Transmitter Communication Failures 

If (bit 7) of status byte-1 is set to 1 the transmitter has a communication problem. 

Details of the error are reported in the rest of the bits (6-0). Status byte-2 is then all zeros. 

Status Byte-1 

7 6 5 4 3 2 1 0 

Bit 6 hex C0 Parity error 

Bit 5 hex A0 Overrun error 

Bit 4 hex 90 Framing error 

Bit 3 hex 88 Checksum error 

Bit 2 hex 80 Always 0 (reserved) 

Bit 1 hex 82 Rx buffer overflow 

Bit 0 hex 81 Always 0 (undefined) 

Status Byte-2 

1 x x x x 0 x 0 

0 0 0 0 0 0 0 0 

7 6 5 4 3 2 1 0 

When status byte-1, bit-7 is a 1, 

all bits in Status byte-2 are set to zero. 


September 19, 2012

0 

Command Response Problems 

If no error is detected in the outgoing communication, the most significant bit (bit 7) of status byte-1 is 

set to 0 and the command response is reported in the rest of the bits (6-0). Status byte-2 contains 

information as to the operational state of the HART device. 

Status Byte-1 

x x x x x x x 

7 6 5 4 3 2 1 0 

Response Codes (integer 0-127): 

0 No command-specific error 

1 (undefined) 

2 Invalid selection 

3 Passed parameter to large 

4 Passed parameter to small 

5 Too few data bytes received 

6 Device-specific command error 

7 In write-protect mode 

8-15 Command Specific (see command) 

16 Access restricted 

17-127 Command Specific (see command) 

32 Device is busy 

64 Command not implemented 

Status Byte-2 

x x x x x x x x 

7 6 5 4 3 2 1 0 

Device Status: 

RETURN 

By Host or Hand Held 

Bit 7 hex 80 Field device malfunction (Note-1) 

Bit 6 hex 40 Configuration Changed 

Bit 5 hex 20 Cold Start (device has reset/power cycled) 

Bit 4 hex 10 

Bit 3 hex 08 

More Status Available 

Loop current fixed 

Issue Command (48) 

Bit 2 hex 04 Loop current saturated (PV out of limits) 

Bit 1 hex 02 Non-primary variable out of limits (SV, TV, FV) (Note-1) 

Bit 0 hex 01 Primary variable out of limits 

Note-1: The result of command-48 may provide additional status detail. 


39

Device-specific status and 

information 

is accessed using 

HART command-48 


September 19, 2012

Command 48 (Common Practice Command) 

� Command 48 requests the device-specific information from a device. 25 status bytes maximum. 

This is command is optional. The 

device vendor does not have to 

implement Command- 48! 

Byte-0 

Host issues Command 48 

Device responds with status 

x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x 


ON/OFF Status 

Byte-1 Byte-2 Byte-3 Byte-4 Byte-5 

Byte-8 Byte-9 Byte-10 

x x x x x x x x x x x x x x x x 

Byte-14 Byte-15 

Byte-20 

Output saturated value 

Byte-6 Byte-7 


(Op-Mode) (Op-Mode) 



41 



x x x x x x x x x x x x x x x x x x x x x x x x 

Output fixed value 

Byte-16 Byte-17 Byte-18 Byte-19 



x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x

Command 48 Example 

� We know that Bit-OFF is normal and Bit-ON is abnormal or information available 

� We do not know what the status bit means! Each Bit and it’s 

associated description is contained in the vendor DD file. DD -Device Descriptor file 

Example: The Honeywell STT250 temperature transmitter uses three of these bytes, as follows: 

Byte-0 Critical Byte-1 Non-Critical Byte-2 Information 

Bit DEVSPCBIT DD-Descriptor Bit DEVSPCBIT DD-Descriptor Bit DEVSPCBIT DD-Descriptor 

0 [0] undefined 

1 [1] Hardware 

Failure 

2 [2] Input Open. 

3 [3] NVM Calib 

Failed 

4 [4] NVM Conf failed 




0 [8] CJ Over Temp 


2 [10] Input out of Spec 

3 [11] Output Saturated 

4 [12] In Output Mode 



7 [15] User Correct 

Active 

0 [16] Suspect Input 







7 [23] 4 wires 

Configuration 

� Status bits can be used in CM’s and graphics by using the TAG/Name. DEVSPCBIT[##] format! 


42

Command-48 Bits used in CM’s 

Honeywell 

STT255 

Temp. Xmtr. 

Command 48 Byte-0 

Bit DEVSPCBIT DD-Descriptor 


1 [1] Hardware 

Failure 

2 [2] Input Open. 

3 [3] NVM Calib 

Failed 

4 [4] NVM Conf failed 




IN(1) IN(2) 

LOGIC: AND 

Control Module 

TT_301B17. DEVSPCBIT[1] 


ANDA 

LOGIC: ONDELAY 

DELATA 

Delay Time 30 sec 

43 

Parameter 

Connector

Cmd-48 and the Alarm Summary 

10/18/02 10:18:43 C2 TT_103B17 Failed H01 Input Open 

TT_103B17 

11/13/2002 10:01:14 

C2 

Honeywell ST255 

Temp xmtr. 

Device Descriptor 

file 

DD 

STT25H 

Ver. 0201 

Very Important! 

The user must ensure that the HART Device Revision number 

matches the template selected when building the HART Device 

Block! 

The actual descriptor from the vendor 

DD will appear in the Alarm Summary 

display for all command-48 status 

returned from a particular HART device! 


44 

RETURN

The Device Variables 

(Slot-0, Slot-1, Slot-2, Slot-3) 

are accessed from the HART 

device using HART 

command-33 


September 19, 2012

Command-33 Concept 

Command 33: read 4 device variables (Slot-0, Slot-1, Slot-2, Slot-3) 

The device vendor determines: 

� If command-33 is supported for a given device! 

� What device variables will be provided! 

� Where the variables are mapped (position 1-255)! 

A HART Device can provide up to 255 variables. 

Example: 

1 Accumulated Valve Travel Inches 

2 Pos. Hi alarm setting Percent 

3 Pos. Lo alarm setting Percent 

4 Deviation alarm setting Percent 

5 Variable EU’s 

. 

. 

. 

255 Variable EU’s 


46

Command (33) Detail 


Device responds with Slot data 

Up to four variables can be requested in the 

command. The data (1-255) in the command 

indicates which four variables are to be returned. 

An entry of zero indicates that no variable is to 

be return for that slot position. 


Parameter Parameter Parameter Parameter 

For 

For 

For 

For 

Slot-0? Slot-1? Slot-2? Slot-3? 

[ ] [ ] [ ] [ ] 

RETURN 


IOM 

Slot-0 [IEEE 754 value] and [ Engr. Units ] 




47

The Device ID Information 

is accessed from the HART 


commands-11, 12, and 13 


September 19, 2012

Device ID Information 


Device responds with data 





Assembly Number 

Manufacturer ID 

Manufacturer Device type 

Number of Preambles 

Universal Command Revision 

Transmitter Command Revision 

Software revision 

Hardware revision 


Tag 

Descriptor 

Date 

Message 

Flags 

Device ID number 

RETURN 

49

The Device Range Information 

is accessed from the HART 


commands-15 


September 19, 2012

Device Range Information 



PV Range Hi = ### 

PV Range Lo = ### 

PV E_units = (DEGF, GPM, etc.) 

PV Damping = ### sec 

Xfer function = linear, sqrt, , etc. 

Upper Range Limit = ### 

Lower Range Limit = ### 

Minimum Span = ### 

RETURN 


51

le User Text 

Text parameters are available for the user to identify what the dynamic and device variables 

represent. 

Body temperature 

Accum. valve travel 


52

HART Cmd-3 (Read Dynamic Variables) 

Command -3 

Data in response 


53 

RETURN 

All Device Vendors must implement this command in the same way! 

Host (I/O module) 

The format and content of the command are 

fully defined by the HART protocol! 


PV value (IEEE -754) 

And the 

PV engineering units 

The format and content of the response are fully 

defined by the HART protocol! 

Primary Variable Secondary Variable Third Variable Fourth Variable 

SV value (IEEE- 754) 

and the 

SV engineering units 

TV value (IEEE- 754) 

and the 

TV engineering units 

QV value (IEEE- 754) 

and the 

QV engineering units 

2-Byte Status 

2-Byte (16 bits) General Device Status 

Byte-1 Byte-2

Command 48 (Common Practice Command) 

� Command 48 requests the device-specific information from a device. 

Byte-0 



(This is optional. The device vendor does not have to implement Cmd- 48) 

� The device can return up to 25 status bytes total. 17 bytes provide for up to 136 ON/OFF status bits. 

� We know that Bit-OFF is normal and Bit-ON is abnormal or information available 

Byte-14 Byte-15 

Byte-20 

� We do not know what the status bit means! Each Bit and it’s 

associated description is contained in the vendor DD file. 

Examples: DD -Device Descriptor file 

Sensor failed 

A/D Failure 


Byte-1 Byte-2 Byte-3 Byte-4 Byte-5 


Output saturated value 

Byte-6 Byte-7 


(Op-Mode) (Op-Mode) 



54 



x x x x x x x x x x x x x x x x x x x x x x x x 

Output fixed value 





RETURN

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