Rockwell Automation 1770-HT8 User Manual

Smart Transmitter Interface Products (HARTr Protocol)

Cat. Nos. 1770-HT1, 1770-HT8, 1770-HT16

User Manual

Important User Information

Because of the variety of uses for the products described in this publication, those responsible for the application and use of this control equipment must satisfy themselves that all necessary steps have been taken to assure that each application and use meets all performance and safety requirements, including any applicable laws, regulations, codes and standards.

The illustrations, charts, sample programs and layout examples shown in this guide are intended solely for purposes of example. Since there are many variables and requirements associated with any particular installation, the Allen-Bradley Company, Inc. does not assume responsibility or liability (to include intellectual property liability) for actual use based upon the examples shown in this publication.

Allen-Bradley Publication SGI-1.1, “Safety Guidelines for the Application, Installation and Maintenance of Solid State Control” (available from your local Allen-Bradley office) describes some important differences between solid-state equipment and electromechanical devices which should be taken into consideration when applying products such as those described in this publication.

Reproduction of the contents of this copyrighted manual, in whole or in part, without written permission of the Allen-Bradley Company Inc. is prohibited.

Throughout this manual we use notes to make you aware of safety considerations:

ATTENTION: Identifies information about practices or circumstances that can lead to personal injury or death, property damage or economic loss.

Attentions help you:

identify a hazard avoid the hazard recognize the consequences

Important: Identifies information that is especially important for successful application and understanding of the product.

Interchange, ControlView, Data Highway Plus and DH+ are trademarks and PLC is a registered trademark of Allen-Bradley Company, Inc.

HART is a registered trademark of Rosemount Inc. IBM is a registered trademark of International Business Machines Corporation.

Preface P1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Purpose Organization How to Use This Manual P1

Related Products P3 Glossary

of the Manual

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Audience P2

AllenBradley HART

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Publications

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of T

erms and Abbreviations P3. . . . . . . . . . . . . . . . . . . . . .

P1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

P1. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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P2. . . . . . . . . . . . . . . . . . . . . . . . . . .

P2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Introducing the Smart Transmitter Interface 11. . . . . . . . . . . .

Product Overview 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1770HT1 Communications Controller 11 1770HT8/16 Terminal Block 13 The

Remote I/O Port of the Communications Controller

The RS232C Port of the Communications Controller 15

The

HAR

T Protocol 18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

HAR

The Poll/Response Mode 110

Burst Mode 110 Features Benefits of Using the Smart Transmitter Interface 111 Compatibility 112

PLC5

HART Field Devices 112

Analog

Hand Held Terminal 113

T Protocol and the Smart Transmitter Interface 19. . . . . .

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of the Smart T

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Family

I/O Devices

ransmitter Interface 110. . . . . . . . . . . . . . . . .

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113. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Installing the Smart Transmitter Interface Products 21. . . . . .

Before You Begin 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Electrostatic Damage 22 Overview of the Installation Procedure 22 Mounting Smart Transmitter Interface Products in a Cabinet 23 Connecting the Communications Controller to the Terminal Blocks 24

Digital Communications Cables 24

Linear Connection 25

Star Connection 26

Star/Linear Connection 27

Connector and Pinout 28 Setting the Board Address Jumpers 29

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Table of Contentsii

Marking the Terminal Block Labels 211. . . . . . . . . . . . . . . . . . . . . .

Connecting the T

Connecting to 1771 I/O Devices 212 Connecting Connecting a Hand Held Terminal 216

Grounding 218

Grounding Grounding

erminal Blocks to I/O and HAR

T Field Devices 211. . .

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to HAR

T Field Devices 213. . . . . . . . . . . . . . . . . . . . .

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the HAR

T Field Device Cable Shield 218. . . . . . . . . . . .

the Analog I/O Cable Shield

218. . . . . . . . . . . . . . . . . .

Supplying Power to the Communications Controller and

Terminal Blocks 219 Fuses for the Communications Controller 219 Connecting Power to the Communications Controller 220

Supplying Loop Power for HART Field Devices 220

Power Supply Requirements 221 Connecting the Power Supply for Loop Power 221

Connecting

the Communications Controller to the RIO Host Termination 223 Activity Indicator 224

Connecting the Communications Controller to the RS232C Host 224

RS232C Baud Rates 224 Cables 224

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Activity Indicator 224 Connector and Pinout 224 Modem Connections 229

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Configuring the Communications Controller 31. . . . . . . . . . .

Overview of Configuration Procedures 31. . . . . . . . . . . . . . . . . . . . .

Displays 31 Push

Configuration Step by Step 33

Enter Configuration Mode 33 Configure Basic Parameters 34 Configure Advanced RS232C Parameters 34 Save and Exit 34 Exit Without Saving 35 Setting Factory Defaults 36

Communication Parameters 36

Basic Parameters 36 Basic Parameters 36 Advanced RS232C Communication Parameters 38

Verifying the Communication Parameters 310

Marking the Communications Controller Label 310

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Buttons

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32. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table of Contents iii

Communicating with the Smart Transmitter Interface 41. . . .

Data Routing and Protocol Conversion 41. . . . . . . . . . . . . . . . . . . . .

Data Routing In Poll and Response Mode 42 Data Routing in Burst Monitor Mode 42 Protocol Conversion 43

of T

Definition

erms 44. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

HART Poll Packets 45

Preamble 45 HART

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Delimiter HART Address 45 HART Command 48 Byte Count 48 Data 49 Check Byte 49

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HART Response and Burst Data Packets 49

Preamble 49 HART HART Address 410 HART Command 411 Byte Count 411 Response Code 412 Data 413 Check Byte 413

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Delimiter

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Smart Transmitter Interface Packets Received by the

Smart Transmitter Interface 414

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Smart Transmitter Interface Command 414 Smart Transmitter Interface Channel 414 Smart Transmitter Interface Control 415 Smart Transmitter Interface Parameter 416 Smart Transmitter Interface Data 416

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Smart Transmitter Interface Packets Sent by the Smart

Transmitter Interface 416

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Smart Transmitter Interface Command 416 Smart Transmitter Interface Channel 417 Smart Transmitter Interface Error Code 417 Smart Transmitter Interface Status 417 Smart Transmitter Interface Data 419

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Valid Smart Transmitter Interface Commands and Responses 419

No Operation (hexadecimal command 00) 420 Enable Poll and Response Mode (hexadecimal command 01) 420 Enable Burst Monitor Mode (hexadecimal command 02) 420 Send Message to Device (hexadecimal command 10) 420 Read Burst Data (hexadecimal command 11) 421 Set Number of Preambles (hexadecimal command 20) 421 Set Number of Retries (hexadecimal command 21) 422

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45. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Table of Contentsiv

Read Status and Statistics (hexadecimal command 30) 422. . . . . . .

Reset Statistics Counters (hexadecimal command 31) 422 Read ID (hexadecimal command 32) 422

Programmable

Short Frame Word Contents  Programmable Controller to Smart

Transmitter Interface (Of

Short Frame Word Contents  Smart Transmitter Interface to

Programmable Controller (Of

Long Frame Word Contents  Programmable Controller to Smart

Transmitter Interface (Of

Long Frame Word Contents  Smart Transmitter Interface to

Programmable Controller (Of

Serial

Communication with the Smart T Full Duplex 435 Half Duplex 435

DF1 Packet Formation 437 Data Highway Plus and the Smart Transmitter Interface 440

Controller Communication with HAR

fset at D9:00)

fset at D9:10)

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fset at D9:40)

ransmitter Interface 434. . . . . .

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T Field Devices 425

428. . . . . . . . . . . . . . . .

430. . . . . . . . . . . . .

431. . . . . . . . . . . . . . . .

433. . . . . . . . . . . . .

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Troubleshooting 51. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Interpreting the Terminal Block LEDs 51. . . . . . . . . . . . . . . . . . . . . .

Interpreting the Communications Controller Status LEDs 52

Interpreting the Communications Controller Numeric Displays 53

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Product Specifications A1. . . . . . . . . . . . . . . . . . . . . . . . . . .

Communications Controller (1770HT1) A1. . . . . . . . . . . . . . . . . . . .

RS232 Interface A1 RIO Interface A1 Terminal Block (1770HT8/16) Interface A1 Electrical A2 Physical A2 Environmental A2

8 Channel Terminal Block (1770HT8) A2

1770HT1 Interface A2 420 mA Current Loop Interfaces (see Figure A.1) A2 Electrical A3 Physical A3 Environmental A3

16 Channel Terminal Block (1770HT16) A3

1770HT1 Interface A3 420 mA Current Loop Interfaces (see Figure A.1) A4 Electrical A4 Physical A4 Environmental A4

HART

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Communications Specifications

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Table of Contents v

DF1 Diagnostic Command Support B1. . . . . . . . . . . . . . . . . .

Diagnostic Command Support B1. . . . . . . . . . . . . . . . . . . . . . . . . . .

Diagnostic Loop B1 Diagnostic Read B2 Diagnostic Diagnostic Counter Reset B3

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Status

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B2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Cable Length and Power Supply Requirements C1. . . . . . . . .

Cabling Requirements Between the Communications Controller

and the Terminal Blocks C1

Maximum Power Cable Lengths C2

Using a Separate Power Supply for a Terminal Block C4

Connecting Power to the Terminal Blocks C4

Cabling and Power Supply Requirements for Loop Power C5

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Preface

Purpose of the Manual

Organization of the Manual

This manual shows you how to use the Smart Transmitter Interface products with Allen-Bradley programmable controllers and other intelligent host computers. It describes how to install and configure the Smart Transmitter Interface products, as well as how to perform trouble-shooting procedures.

This manual contains five chapters and three appendices. They address the following topics:

Chapter Topics Covered

Chapter 1: Introducing the Smart Transmitter Interface

Chapter 2: Installing the Smart Transmitter Interface

Chapter 3: Configuring the Communications Controller

Chapter 4: Communicating with the Smart Transmitter Interface

Chapter 5: Troubleshooting diagnosing communications problems

Appendix A: Product Specifications technical specifications for 1770HT1, HT8 and

Appendix B: DF1 Diagnostic Command Support diagnostic commands for use on the RS232C

Appendix C: Cable Length and Power Supply Requirements

overview of the Smart Transmitter Interface; introduction to the HART protocol, and features and benefits of using them

installation procedure, power supply requirements and connection instructions

the communication parameters and how to set them on the Communications Controller

Smart Transmitter Interface data routing and protocol conversion, communication terms, HART and Smart Transmitter Interface data packets, PLC5 programming example, and serial host communication with the Smart Transmitter Interface

HT16, and HART communications specifications

link between a host processor and the Communications Controller

cable length requirements between the Communications Controller and the Terminal Blocks, and power supply requirements

How to Use This Manual

This manual explains the features, functions and specifications of three products designed to provide communication between Allen-Bradley products and HARTr field devices. These products are:

Communications Controller Cat. No. 1770-HT1

P-1

Preface

8 Channel Terminal Block Cat. No. 1770-HT8

16 Channel Terminal Block Cat. No. 1770-HT16

Audience

This manual is intended for use by:

persons installing Smart Transmitter Interface products, in connection

with Allen-Bradley PLC controllers or other intelligent controllers

system integrators who are designing and establishing network systems

involving plant floor machinery, programmable controllers, HART field devices, Smart Transmitter Interface products and host computers

maintenance personnel who maintain such systems and who must

locate, define and correct problems arising during their day-to-day operation

Related Publications

AllenBradley Publications

Publication Reference Number and Date

AllenBradley Data Highway/Data Highway Plust/DH485 Communication Protocol and Command Set Reference Manual

Analog Input Module User Manual cat. no. 1771IFE 17716.5.90, September 1991

ControlView Core User Manual 61906.5.1, November 1992

PLC5 Family Programmable Controllers Hardware Installation Manual

PLC5 Programming Software 62006.4.7

6008SI IBM PC Scanner User's Manual

17706.5.16, November 1991

17856.6.1

60086.5.3

A complete list of publications relating to ControlView and its options is available in the ControlView Core User Manual. For a list of publications on Allen-Bradley programmable controller products refer to the Allen-Bradley publication index (SD499).

HART Publications

Publication Reference Number and Date

HART - Smart Communications Protocol Specification

Revision 5.1, January 4, 1991 Rosemount, Inc. Document No. D9000047, Revision A

P-2

Preface

Related Products

Glossary of Terms and Abbreviations

The Smart Transmitter Interface Products create a communication interface between programmable controllers and HART field devices. They are compatible with HART field devices and with hand-held terminals capable of supporting the physical and data link layers of the HART protocol.

This manual uses the following terms as defined below. Actuator: any one of several field devices that provide control functions

using a 4-20mA input control signal. Actuators that support the HART protocol are designated as being “smart”.

BTR: Block Transfer Read BTW: Block Transfer Write Clear: (a bit) equal to 0 Hand-held terminal: a smart terminal product capable of functioning as

either a primary or secondary master to one single HART device, using the HART protocol; this terminal allows the operator to monitor and configure the HART field device (e.g. Rosemount 268)

HART: Highway Addressable Remote Transducer HART field device: a transducer or actuator that supports the HART

protocol

- 4-wire: refers to a HART field device drawing power from an external power source

- 2-wire: refers to a HART field device drawing power from the 4-20 mA loop

HART protocol: a protocol that provides digital communication over an industry-standard 4-20 mA process control loop at the same time as the value of a process control variable is being transmitted as a 4-20 mA signal

Host Processor: the programmable controller or host computer (generally a PC) connected to the Communications Controller over the RIO, or the host computer connected to the Communications Controller’s RS-232 port

mA: milliamp; one-thousandth of an Ampere Multidrop: multiple HART field devices (to a maximum of 15), connected

in parallel, per channel on a terminal block PLC: Programmable Logic Controller; an Allen-Bradley programmable

controller

P-3

Preface

Point-to-point: one HART field device per channel on a terminal block RIO: Remote Input Output link that supports remote, time-critical, I/O

and control communications between a master PLC controller and its remote I/O and adapter mode slave processors

Transducer/Transmitter: any one of several field devices that can measure pressure, temperature, level, flow, density or other process control variables, and then transmit the value of that variable as a 4-20 mA signal. Transducers that support the HART protocol are designated as being “smart”.

P-4

Chapter

Introducing the Smart Transmitter Interface

This chapter provides an overview of the Smart Transmitter Interface products, a brief introduction to the HART protocol and a description of the different system architectures which can be implemented. It also describes the features and benefits of using the Smart Transmitter Interface and lists some of the products that are compatible with the 1770-HT1, 1770-HT8 and 1770-HT16.

Product Overview

The Smart Transmitter Interface products provide a communication interface between Allen-Bradley PLC controllers or host computers and HART field devices (transmitters, transducers and actuators). These products give host processors access to the digital information encoded with the 4-20 mA analog process control signal. The digital information can be passed to and from the host processor using either a remote I/O (RIO) or an RS-232C port.

A Smart Transmitter Interface consists of one Communications Controller (1770-HT1), and one or more Terminal Blocks (1770-HT8 or 1770-HT16). These products can be mounted on a DIN rail in a control cabinet and the field wiring brought directly to the Terminal Blocks.

1770HT1 Communications Controller

The 1770-HT1 Communications Controller receives commands from a host processor and passes them on, via the 1770-HT8/16 Terminal Blocks, to HART field devices. Responses from the HART field devices go through the Terminal Blocks to the Communications Controller and then on to the host processor.

The Communications Controller communicates through its Remote I/O or RS-232C port to the host processor. The combination of hardware and software used by the host determines which port is used.

Use the Remote I/O port (labelled RIO in Figure 1.1) with the following:

a programmable controller as host processor using ladder logic to

perform block transfer reads and writes. On the DH+ network the programmable controller can connect to a computer running software applications, such as ControlView, to monitor and supervise the ongoing processes.

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Chapter 1

Introducing the Smart Transmitter Interface

a programmable controller with Allen-Bradley’s pass-through

functionality connected to a host computer on the DH+ network running application software to initiate communications

Use the RS-232C port (labelled RS-232 in Figure 1.1) with the following:

a host computer using Allen-Bradley DF1 protocol, connected to the

Communications Controller by an RS-232 cable (if the distance is less than 50 feet)

a host computer using Allen-Bradley DF1 protocol, connected to the

Communications Controller by telephone lines and modems

The Communications Controller requires an external 24 VDC power supply. It provides a multiplexed, 32 channel interface to the Terminal Blocks. All of the Remote I/O and RS-232C communications parameters are set on the Communications Controller using push buttons and a seven segment LED display.

RS-232C

Connector

1 SH 2 RIO

POWER

RIO

RS-232

HART

FAULT

VIEW DATA EXIT

SAVE

Push Button Switches

RIO - Connector

Status LEDs

OPTN

1 2 3 4 5 6 7 8

7-Segment LED

Display

Figure 1.1 1770HT1

Parameter # Parameter

OPTION

NOTES

OPTNDATA DATA

7. A.

User writeable

areas

Communications Controller

DATA

Setting

Power Connector

Power Fuse

SMART TRANSMITTER COMMUNICATIONS CONTROLLER

Connector to Terminal Block(s)

+ - 24 VDC

HT8/HT16 INTERCONNECT

90002

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Chapter 1

Introducing the Smart Transmitter Interface

1770HT8/16 Terminal Block

The Terminal Blocks pass both analog and digital signals to and from the HART field devices. The analog signal is passed on to devices such as the Allen-Bradley 1771-IFE Analog I/O module. The digital signal is routed to the Communications Controller.

Each Terminal Block provides either 8 (1770-HT8) or 16 (1770-HT16) channels. Each channel has connection points for HART field devices and Analog I/O modules, loop fuses and loop power selection jumpers. Any combination of 8 and 16 channel Terminal Blocks can be used to make up the 32 channel maximum. The board address jumpers (see Figure 1.2 and Figure 1.3) indicate to the Communications Controller which set of channels a particular Terminal Block will use. These are set when the Terminal Block is installed (see Chapter 2).

Figure 1.2 1770HT8

Connection to Communications

Controller or other Terminal Blocks

Board Selected LED

CATALOG NO. 1770-HT8 VOLTS 24 VDC

HT1/HT8/HT16 INTERCONNECT

User writeable area

Jumpers to select Loop Power

8 Channel T

CHANNEL

TERMINAL BLOCK

erminal Block

Analog I/O Module

Connector

Board Address

Jumpers

1 2 3 4 5 6 7 8 RTN SH

JP1 JP1

JP1

E D

CH 1 CH 2 CH 3 CH 4

1 2 SH 1 2 SH 1 2 SH 1 2 SH

E D

E D E D

HART Transmitters -

Connectors

Loop

Power

LED

JP1

JP1 JP1

E D

CH 5 CH 6 CH 7 CH 8

1 2 SH 1 2 SH 1 2 SH 1 2 SH

Power Fuse

JP1

E D

Loop Fuses

Power Connector

+ Loop Power

JP1

E D

90018

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Chapter 1

Introducing the Smart Transmitter Interface

Connection to Communications

Controller or other Terminal Blocks

Board Selected LED

CHANNEL

TERMINAL BLOCK

CATALOG NO. 1770-HT8 VOLTS 24 VDC

HT1/HT8/HT16 INTERCONNECT

User writeable area

Jumpers to select Loop Power

Board Address

Jumpers

Figure 1.3 1770HT16

JP1 JP1

E D

CH 1 CH 2 CH 3 CH 4

1 2 SH 1 2 SH 1 2 SH 1 2 SH

16 Channel Terminal Block

JP1

E D

E D E D

1 2 3 4 5 6 7 8 RTN SH

JP1

JP1 JP1

E D

CH 5 CH 6 CH 7 CH 8

1 2 SH 1 2 SH 1 2 SH 1 2 SH

Analog I/O Module

JP1

E D

HART Transmitters -

Connectors

Connector

1 2 3 4 5 6 7 8 RTN SH

JP1

JP1 JP1

E D

CH 1 CH 2 CH 3 CH 4

1 2 SH 1 2 SH 1 2 SH 1 2 SH

Loop

Power

LED

Power Fuse

E D

JP1

JP1 JP1

E D

CH 5 CH 6 CH 7 CH 8

1 2 SH 1 2 SH 1 2 SH 1 2 SH

JP1

E D E D

Loop Fuses

Power Connector

+ - Loop Power

JP1

E D

JP1

90017

The Remote I/O Port of the Communications Controller

Programmable Controller Host Communications

Using programmable controller ladder logic to initiate Block Transfer Writes and Reads (BTW and BTR), data can be sent to and received from the HART field devices. A host computer on the DH+ network running application programs (such as ControlView) can read and display the data which the programmable controller has obtained from the HART field devices. (See Figure 1.4)

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Figure 1.4

Smart

ransmitter Interface with Programmable Controller Host

Chapter 1

Introducing the Smart Transmitter Interface

CONTROLVIEW

DH+

Programmable

Controller with

Ladder Logic

RIO

Smart

Transmitter

Interface

HART

Field

Devices

90032

DH+ Host Communications (Using Programmable Controller Pass-through)

Data can also be sent to and received from HART field devices using the pass-through feature of the programmable controller to initiate Block Transfer Reads and Writes (BTR and BTW). No dedicated programmable controller ladder logic programs are required when the pass-through feature is used. A host computer on the DH+ network, running programs with pass-through support, can be used to communicate with the HART field devices.

Figure 1.5

Smart (Using Passthrough)

ransmitter Interface with DH+ Host

THIRD

PARTY

SOFTWARE

DH+

Programmable Controller with

Passthrough

Feature

RIO

Smart

Transmitter

Interface

HART

Field

Devices

The RS232C Port of the Communications Controller

The RS-232C port on the Communications Controller allows the HART field devices to communicate with either a local host or, via modem, a remote host.

90033

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Chapter 1

Introducing the Smart Transmitter Interface

Full Duplex Communications

With DF1 full duplex systems, you can communicate directly to a single Smart Transmitter Interface. No programmable controllers are necessary—just a computer running the appropriate software, the HART field devices, and the Smart Transmitter Interface between them. The host computer and the Smart Transmitter Interface should be connected with either an RS-232 cable for distances equal to or less than 50 feet, or two modems for distances greater than 50 feet. (See Figure 1.6 and Figure 1.7.) This gives end users with less complex applications, inexpensive access to HART field devices and to the advantages of the HART protocol.

Figure 1.6

Duplex Communication with no Modem

Full

HOST COMPUTER

RS-232 CABLE

HOST COMPUTER

Figure 1.7

Duplex with Modems

Full

RS-232 CABLE

Smart

Transmitter

Interface

Smart

Transmitter

Interface

HART

Field

Devices

90050

HART

Field

Devices

90049

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Chapter 1

Introducing the Smart Transmitter Interface

Half Duplex Communications

DF1 half duplex systems can be considerably more extensive. The host computer can communicate via modems to a number of Smart Transmitter Interfaces spread out over great distances. Once again, though programmable controllers can certainly be a part of such a network, they are not required, and any host with third party software can be used with the Smart Transmitter Interface.

Figure 1.8

Duplex Communications with Modems

Half

Half Duplex

ETC.

MODEM

HOST COMPUTER

Smart

Transmitter

Interface

Smart

Transmitter

Interface

HART

Field

Devices

HART

Field

Devices

90048

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Chapter 1

Introducing the Smart Transmitter Interface

The HART Protocol

The HART field communications protocol carries digital information with the analog signal over industry-standard 4-20 mA process control loops. Both the digital and analog signals occur simultaneously on the same loop wiring without disrupting the process signal.

The HART protocol uses the Frequency Shift Keying technique, based on the Bell 202 communication standard. Digital communication is accomplished by superimposing a frequency signal over the 4-20 mA current, as shown in Figure 1.9. Two individual frequencies, 1200 and 2200 Hz, represent the digits 1 and 0. The sine wave formed by the two frequency levels has an average value of zero, so digital communication takes place without disruption to the analog signal.

Figure 1.9 Analog

and Digital Signals on 420 mA Current

+0.5 mA

Analog Signal

90047

-0.5 mA

1200 Hz 1"

Average Current Change During Communication = 0

2200 Hz 0"

Field devices (transducers, actuators) can use the HART protocol to transmit or receive a process variable as a 4-20 mA analog signal at the same time as they are transmitting or receiving device or process data (e.g. smart pressure, temperature, density, etc.) as a modulated digital signal. The analog signal, with its faster update rate, can be used for control, while the digital signal can be used for diagnostic, maintenance and additional process data. Communication can be in either poll/response or burst transmission mode.

The HART protocol supports digital communication from both a control system and a hand-held communications device. It also allows multidrop networking by which several smart HART field devices can be connected to a single twisted-pair wire, and can operate over leased telephone lines.

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Chapter 1

Introducing the Smart Transmitter Interface

The HART Protocol and the Smart Transmitter Interface

Each Communications Controller can communicate with a maximum of 32 channels via the 1770-HT8 and 1770-HT16 Terminal Blocks. As all channels are multiplexed, communications can only occur over one channel at a time. Each channel can have one HART field device connected to it in point-to-point mode, or up to 15 devices in a multidrop network. The host addresses these channels using channel numbers 0–31 (decimal).

The Communications Controller in the Smart Transmitter Interface receives HART protocol commands from the host processor (via Remote I/O or RS-232C connection) and routes these commands (via the Terminal Blocks) to the HART field devices. The Smart Transmitter Interface receives responses from the HART field devices and transmits the responses to the host when it polls for them.

In both multidrop and point-to-point networks each device has a unique address that is included in every HART message. A device picks up messages destined to it via this unique address.

When the Terminal Block receives the composite digital/analog signal from the HART field devices, it filters out the digital portion of the signal (see Appendix A for more information on the filtering circuitry), and passes the analog portion on to an Allen-Bradley Analog I/O module, such as the 1771-IFE. The Analog I/O module decodes the analog data and passes it along to the programmable controller.

At the same time, the Terminal Block reads the digital portion of the signal and multiplexes it to the Communications Controller. The Communications Controller embeds the digital data into messages conforming to the RIO or DF1 protocol format, and passes it to the appropriate host processor and its application program in one of three ways:

to a programmable controller via the remote I/O link

to a computer via the RS-232C port

to a host on the Data Highway Plus network via the pass-through feature

of an Allen-Bradley PLC-5 family programmable controller

Important: You cannot have more than one DH+ host computer using the pass-through feature or more than one RS-232C host.

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Chapter 1

Introducing the Smart Transmitter Interface

Poll/Response Mode

The HART protocol supports two modes of digital communications, poll/response and burst. In poll/response mode the host processor requests information from (polls) the smart device. Both point-to-point and multidrop networks can employ this mode.

When the host processor sends a request or control information to the HART field devices, the Smart Transmitter Interface reads the routing information in the header portion of the data. It then strips the header off the message and sends the data down the appropriate channel to the HART device. Responses from the HART devices are returned to the host processor when the host polls for them.

If there are no more messages to be forwarded, the Smart Transmitter Interface stays on the last used channel and watches the traffic. This allows higher throughput if consecutive messages are sent to the same channel.

Features of the Smart Transmitter Interface

Burst Mode

In burst mode the HART field device continuously transmits digital data to the Communications Controller in burst monitor mode without the need for request messages from the host. This mode cannot be used with multidrop networks.

In burst monitor mode, the host processor sends the Smart Transmitter Interface a list of all the channels whose devices are preset to burst mode. If the list changes, the host must provide a new list. The Smart Transmitter Interface continuously monitors the channels on the list in order, returning to the first as soon as the last has been checked. The data collected from the burst channels is stored in a Burst Data table. The latest information on any channel is sent to the host processor upon request.

While in burst monitor mode, the Smart Transmitter Interface still responds to requests from the host to poll any channel. When the polling is complete, it resumes monitoring the burst channels.

The Smart Transmitter Interface (1770-HT1 and 1770-HT8/16) features include:

1-10

remote I/O port for interface to programmable controllers (RIO

scanners) and DH+ hosts

RS-232C port for interface to serial hosts

7-segment display and push buttons for communications configuration

Chapter 1

Introducing the Smart Transmitter Interface

clips for DIN rail mounting

connections to 32 HART field devices in point-to-point configuration

point to point and multidrop wiring support

poll and response or burst digital transmission mode support

connector for providing loop power

interface to Analog I/O modules with 4-20 mA loop support

2 wire and 4 wire transmitters supported

Benefits of Using the Smart Transmitter Interface

The benefits of using the Smart Transmitter Interface to take advantage of the HART protocol include the following:

extend programmable controller use in the process area by enabling

Allen-Bradley PLCs to communicate with HART field devices, thus allowing process monitoring with ControlView or similar applications software

Because of the added intelligence supplied by the HART field devices, and the wide range of accurate data available from such devices, (pressure, temperature, level, flow and density, among others), automated processes can be monitored accurately over considerable distances.

reduce downtime and installation time through remote wiring

verification, remote transmitter programming and simple retrofitting capabilities of HART field devices

Many HART devices are “smart” enough to tell you what is wrong with them, and how they can be readjusted by remote programming. They can be, in effect, remote diagnostic tools, as well as remote repair units. Maintenance becomes simpler and less costly since you no longer need to send technicians out to the field to perform these tasks manually.

add Smart device capabilities to existing analog systems while

maintaining existing devices

You can add the Smart Transmitter Interface to an existing 4-20 mA system without having to change the wiring, thus reducing installation time and expense. Digital capabilities can be gradually implemented, including digital process variables monitoring, without modifying field devices.

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Chapter 1

Introducing the Smart Transmitter Interface

perform configuration and diagnostics of HART field devices using

third party software and the pass-through feature

Compatibility

The Smart Transmitter Interface Products create a communication interface between programmable controllers and HART field devices. (See Figure 1.10.)

The Smart Transmitter Interface is compatible with HART field devices and with hand-held terminals capable of supporting the physical and data link layers of the HART protocol.

Host computers can be any 100% PC compatible computers.

The following products have been tested in connection with the Smart Transmitter Interface:

PLC5 Family

PLC-5/11

PLC-5/15

PLC-5/20

PLC-5/25

1-12

PLC-5/30

PLC-5/40

PLC-5/60

PLC-5/250

You can connect one or more Smart Transmitter Interfaces directly to a PLC-5 Remote I/O Port (in scanner mode) along with other I/O racks. In addition, the Smart Transmitter Interface can also be connected to other remote I/O scanner modules such as the 1771-SN I/O Subscanner module. For details about which programmable controllers support the pass-through feature, contact your A-B representative.

HART Field Devices

ABB Kent Taylor K-SC

ABB Kent Taylor K-ST

Chapter 1

Introducing the Smart Transmitter Interface

Fischer & Porter 50XM1000B

Micro Motion RFT9739

Moore Products 340B

Princo 50PL4610

Rochester Instrument System SC-6500

Rosemount 1151S

Rosemount 3001C

Rosemount 3001S

Rosemount 3044C

Rosemount 3051C

Rosemount 8712C

Rosemount 8800

Rosemount 9712

Rosemount Analytical 2054pH

Smar LD301

Analog I/O Devices

1771-IE05

1771-IF

1771-IFE

Hand Held Terminal

Rosemount Model 268 Smart Family Interface

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Chapter 1

Introducing the Smart Transmitter Interface

Figure 1.10

ypical Network

Host Computer

1770

1771ASB RIO Adapter

HT1

DH+

RIO

PLC5

1771IFE Modules

Shielded Cables

- max. 30 ft.

1770HT16

1770HT8

Point-to-point

1771IFE

HART

Field

Devices

1770HT8

Cable

- max. 10000 ft.

Multidrop

90027

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Chapter

Installing the Smart Transmitter Interface Products

This chapter explains how to install the Smart Transmitter Interface products. It includes the following information:

an overview of the general installation procedure

how to connect the Communications Controller and Terminal Blocks to

each other so they can communicate

how to connect Terminal Blocks to Analog I/O and HART field devices

Before You Begin

system grounding requirements

power supply requirements and connections for the Communications

Controller and Terminal Blocks

how to provide power for HART field devices through the Terminal

Blocks

how to connect the Communications Controller to the host processor

Before installing the Smart Transmitter Interface you should:

determine where the Communications Controller and Terminal Blocks

are to be placed

The Terminal Blocks should be mounted in the same equipment cabinet as the Analog I/O modules to which they are to be connected. The distance between a given Terminal block and its HART field devices must conform to the HART Protocol specifications and meet the requirements in Appendix C.

review your setup to ensure that the maximum cable length between the

Communications Controller and the Terminal Blocks is not exceeded. See the section Connecting the Communications Controller to the Terminal Blocks for details.

calculate the power requirements of the Communications Controller

(1770-HT1), the Terminal Blocks (1770-HT8/16) and the HART field devices

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Chapter 2

Installing the Smart Transmitter Interface Products

Electrostatic Damage

Overview of the Installation Procedure

Electrostatic discharge can damage semiconductor devices inside the Smart Transmitter Interface products. To guard against electrostatic damage, observe the following precautions:

wear an approved wrist strap grounding device, or touch a grounded

object to rid yourself of electrostatic charge before handling the products

keep the products in their static-shield bags when not in use

The general procedure for installing the Smart Transmitter Interface products is as follows:

1. Mount the Communications Controller and the Terminal Blocks in

their appropriate equipment cabinet (or cabinets).

2. Connect the Communications Controller to the Terminal Blocks and

set the board address jumpers on the Terminal Blocks.

3. Connect the Terminal Blocks to I/O modules (1771 I/O devices) and

HART field devices.

4. Establish the necessary ground connections.

5. Connect the Communications Controller and Terminal Blocks to a

power supply.

6. Configure the communications parameters on the Communications

Controller as detailed in Chapter 3.

7. Connect the Communications Controller to the host through the RIO

or RS-232C port.

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Chapter 2

Installing the Smart Transmitter Interface Products

Mounting Smart Transmitter Interface Products in a Cabinet

Foot

DIN Rail

Mount the Terminal Blocks in the same equipment cabinet as the Analog I/O modules to which they will be connected. This ensures the integrity of the 4-20 mA analog signal being received by the Analog I/O module.

Each unit of the Smart Transmitter Interface is equipped with two plastic feet designed to attach to an EN 50 022 or EN 50 035 DIN rail. Using these feet, clip the unit(s) to the DIN rail in the desired position (Figure 2.1). The units can be mounted in any orientation—horizontally, vertically, diagonally, etc.

Figure 2.1 Mounting

on a DIN Rail

90037

Foot

DIN Rail

To release the feet from the rail, press on the plastic as shown in Figure 2.2 so that the clip is pulled back far enough to release the unit.

Figure 2.2 Releasing

From a DIN Rail

Press Here

90038

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Chapter 2

Installing the Smart Transmitter Interface Products

Connecting the Communications Controller to the Terminal Blocks

The Communications Controller can support a maximum of 32 HART channels via the Terminal Blocks. Use any of the following combinations:

one or two 16 Channel Terminal Blocks (1770-HT16)

one, two, three or four 8 Channel Terminal Blocks (1770-HT8)

one 16 Channel Terminal Block and one or two 8 Channel Terminal

Blocks

Digital Communications Cables

The connecting cables should be shielded multi-conductor cables with 8 twisted 20-24 AWG wire pairs. These are not supplied with the Smart Transmitter Interface. Belden #9508 (24 gauge) or # 85168 cable (20 gauge) or equivalent is recommended. Line 1 is shield, line 2 power and lines 3 to 17 are control.

The connections between the Communications Controller and the Terminal Blocks can be either a linear or star topography. You can use any combination of linear/star connections as long as you adhere to the cabling length requirements.

If your particular setup requires cable lengths greater than the ones indicated in Figure 2.3 to Figure 2.5 or is substantially different, refer to Appendix C.

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Chapter 2

Installing the Smart Transmitter Interface Products

Linear Connection

For linear connection the cables go from the 17 pin connector on the Communications Controller to the connector on the first Terminal Block. Another cable of the same kind leads from the connector on the first Terminal Block to the connector on the second Terminal Block, from there to the connector on the third Terminal Block, and so on.

1770

Figure 2.3 Example

1: Linear Connection

+ -

HT1

1770HT16

1770HT8

Example 1 assumes that the modules (HT1, HT16 and two HT8’s) are installed in separate cabinets. The maximum cable lengths allowed for the setup shown in this example are given in the table below.

+ -

1770HT8

+ -

90031

Cable Size Cable a Cable b Cable c

Belden # 85168 250 ft 250 ft 250 ft

If you are using a linear arrangement, the connector at the Communications Controller will have one set of 17 wires leading out of it. The connector at each Terminal Block (except the last one) will have two sets of wires in the same holes: the one coming from the previous connection, (either the Communications Controller or the previous Terminal Block), and the one leading to the next Terminal Block.

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