HART-enabled PLC analog input module reference design


Design files


This reference design is a single-channel, 4-mA to 20-mA analog input module that supports the highway addressable remote transducer (HART) communication protocol, enabling bidirectional digital communication between field transmitters and programmable logic controllers (PLCs). The loop current, representing the primary variable, flows through a current-sense resistor producing a proportional voltage that is digitized by a precision delta-sigma analog-to-digital converter (ADC) (ADS1260). A DAC8740H modem is used in this design to implement HART communication across the current loop. The ADS1260 and DAC8740H are interfaced with an external microcontroller that controls the ADS1260 sampling and includes a HART software stack to support the HART protocol. This design also features digital isolation, a wide power-supply range, and a high-precision external voltage reference for the ADC.

  • 4-20 mA analog input with HART modem
  • High accuracy loop current measurement < 0.05% FSR TUE
  • HART physical layer compliance tested
  • 6V-28V power supply input
  • 20 effective bits for loop-current measurement

A fully assembled board has been developed for testing and performance validation only, and is not available for sale.

Design files & products

Design files

Download ready-to-use system files to speed your design process.

TIDUEG0.PDF (1153 K)

Reference design overview and verified performance test data


Detailed schematic diagram for design layout and components


Complete listing of design components, reference designators, and manufacturers/part numbers


Detailed overview of design layout for component placement


Files used for 3D models or 2D drawings of IC components


Design file that contains information on physical board layer of design PCB


PCB layer plot file used for generating PCB design layout


Includes TI products in the design and potential alternatives.

Digital isolators

ISO7741Robust EMC, quad-channel, 3/1, reinforced digital isolator

Data sheet document-pdfAcrobat PDF open-in-new HTML
Digital isolators

ISO7742Robust EMC, quad-channel, 2/2, reinforced digital isolator

Data sheet document-pdfAcrobat PDF open-in-new HTML
Linear & low-dropout (LDO) regulators

TLV760100-mA, 30-V, low-dropout voltage regulator

Data sheet document-pdfAcrobat PDF open-in-new HTML
Precision ADCs (<=10MSPS)

ADS126024-bit, 40-kSPS, 5-ch delta-sigma ADC with PGA, VREF and IDACs for factory automation

Data sheet document-pdfAcrobat PDF open-in-new HTML
Precision DACs (<=10MSPS)

DAC8740HHART®, FOUNDATION Fieldbus™, and PROFIBUS PA-compliant modem with UART interface

Data sheet document-pdfAcrobat PDF open-in-new HTML
Series voltage references

REF34252.5-V, low-drift, low-power, small-footprint series voltage reference

Data sheet document-pdfAcrobat PDF open-in-new HTML

Technical documentation

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Type Title Date
* Design guide HART Enabled PLC Analog Input Module Reference Design Oct. 24, 2018

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