SLAAEH8
October 2024
AFE781H1
,
AFE782H1
,
AFE881H1
,
AFE882H1
,
DAC8740H
,
DAC8741H
,
DAC8742H
1
Abstract
Trademarks
1
Introduction
1.1
The 4-20mA Loop
1.2
The HART Protocol
1.2.1
Adding HART to the 4-20mA Loop
1.2.2
HART FSK
2
AFE881H1 HART Modem
2.1
AFE881H1 HART Transmitter
2.2
Detailed Schematic
2.2.1
Input Protection
2.2.2
Startup Circuit
2.2.3
Voltage-to-Current Stage
2.2.4
Voltage-to-Current Calculation
2.2.5
HART Signal Transmission
2.2.6
HART Input Protection
2.2.7
Current Consumption
2.2.8
HART Transmitter Board
2.2.9
HART Protocol Stack
3
HART Testing and Registration
3.1
HART History and the FieldComm Group
3.2
HART Testing Overview
3.2.1
HART Protocol Specifications
3.2.2
HART Protocol Test Specifications
3.2.3
Remote Transmitter Device Testing
3.3
HART Test Equipment
3.4
HART Physical Layer Testing
3.4.1
FSK Sinusoid Test
3.4.2
Carrier Start and Stop Time Tests
3.4.3
Carrier Start and Stop Transient Tests
3.4.4
Output Noise During Silence
3.4.5
Analog Rate of Change Test
3.4.6
Receive Impedance Test
3.4.7
Noise Sensitivity Test
3.4.8
Carrier Detect Test
3.5
Data Link Layer Tests
3.5.1
Data Link Layer Test Specifications
3.5.2
Data Link Layer Test Logs
3.6
Universal Command Tests
3.7
Common-Practice Command Tests
3.8
Device Specific Command Tests
3.9
HART Protocol Test Submission
3.10
HART Registration
4
Other TI HART Modem Designs
5
Summary
6
Acknowledgments
7
References
7
References
Texas Instruments,
AFEx81H1 16-Bit and 14-Bit, Low-Power DACs With Internal HART® Modem, Voltage Reference, and Diagnostic ADC for 4-mA to 20-mA Loop-Powered Applications
, data sheet.
Texas Instruments,
AFEx82H1 16-Bit and 14-Bit, Low-Power DACs With Internal HART® Modem, Voltage Reference, and Diagnostic ADC for 4-mA to 20-mA Loop-Powered Applications
, data sheet.
Texas Instruments,
DAC874xH, HART and FOUNDATION Fieldbus / PROFIBUS PA Modem
, data sheet.
Texas Instruments,
DAC8742H, HART and FOUNDATION Fieldbus / PROFIBUS PA Modem
, data sheet.
Texas Instruments,
AFE881H1EVM User's Guide
, user's guide.
Texas Instruments,
AFE882H1EVM User's Guide
, user's guide.
Texas Instruments,
A Basic Guide to the HART Protocol
, application note.
Texas Instruments,
Highly-Accurate, Loop-Powered, 4mA to 20mA Field Transmitter With HART Modem Reference Design
, reference design.
Texas Instruments,
HART-enabled PLC analog input module reference design
, reference design.