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 https://github.com/kmihaylov/modbusino) a delay may occur after sending a message (more information can be found in the PR thread #2043, #2043 (comment)).
.. envvar:: RS485_RE_PIN Default: 15 GPIO pin number for RE (Receive-Enable) output.
.. envvar:: RS485_TX_LEVEL Default: HIGH. Active level for RE pin during transmission.