This is the RS-485 MicroLink-HM, a managed HART interface that can be used as a primary or secondary HART master - 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 - or use the free included HM Configuration app. See 101-0029 for the MicroLink-HM with RS-232 interface.

MicroLink-HM RS-485 Manual (PDF)
Quick Start Guide (PDF)

HM Configuration app
HART device polling address setup app
Application Note 620-0026 - Using Modbus with the MicroLink-HM


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

  • RS-485 port allows multiple modems on the same network

  • DIN Rail Mounted (35mm)

  • Wide 5 to 30 Vdc supply range

  • LED provides HART communications status

  • Compatible with USB to RS-485 serial converter cables

  • RS-485 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

  • Includes HM Configuration app and HART device addressing app

  • Includes PACTware and Microflex Generic HART DTM-6 on a CD