InLink-HM is a complete HART modem module that can be used as a primary or secondary HART host - eliminating the need for external carrier detect (CD) monitoring and request-to-send (RTS) control. It can also be configured to continuously poll up to 16 HART devices, filling internal Modbus registers with variable values.  The variable values can then be read as 16-bit signed integer or single precision floating point using Modbus-RTU commands. Configuration is saved in Modbus registers allowing Modbus commands to be used for configuration. InLink-HM uses the same modem and core processor that the MicroLink-HM modems use. 

InLink-HM Manual (PDF)
InLink-HM Datasheet (PDF)
> HM Configuration App
> HART Protocol Host App
> RS-232 InLink Evaluation Board
> RS-485 InLink-HM Evaluation Board

Application note: Getting Started with InLink-HM (PDF)


  • Can be used as a standard HART protocol modem or HART to modbus accumulator for OEM applications

  • Small 1.1" x 1.25" PCB footprint - same pin-out as InLink-TC modem

  • Through-hole or socket mounting

  • Low-power 3.3 volt supply

  • HART communications status output pin

  • Serial port can be set to standard baud rates from 1200 to 57600 O, E, N parity

  • Complies with HART physical layer

  • Transformer isolation simplifies loop connections and eliminates grounding effects

  • Use standard modbus commands to read HART device variable data

  • Free HM Configuration app and HART device addressing app available

  • Free PACTware and Microflex Generic HART DTM-6 available

  • Compatible with the 101-0003 InLink evaluation board

InLink-HM Block Diagram