modbusino RTU Library (modbus slave)

modbusino is lightweight RTU Modbus slave library that supports ‘read holding registers’ and ‘write multiple registers’ functions. Please note that prior to commit 02dff3c (branch Sming, port URL a delay may occur after sending a message (more information can be found in the PR thread #2043,

Configuration variables


Default: 15

GPIO pin number for RE (Receive-Enable) output.


Default: HIGH.

Active level for RE pin during transmission.


Used by

Environment Variables

SoC support

  • esp32

  • esp32c2

  • esp32c3

  • esp32s2

  • esp32s3

  • esp8266

  • host

  • rp2040

Submodule: modbusino