Modbus Error: [Input/Output] No Response received from the remote unit

Question

I\' trying to connect from my Mac laptop to a Modbus device (MR-SI4) using a serial connection using a USB RS485 converter that gets \"mounted\" to /dev/cu.SLAB_USBtoU

Answer 1

I was able to work around this issue by setting the constant RetryOnEmpty to True.

from pymodbus.constants import Defaults
Defaults.RetryOnEmpty = True

It also may be useful to configure a timeout and some retries.

Defaults.Timeout = 5
Defaults.Retries = 5

https://pymodbus.readthedocs.io/en/v1.3.2/library/constants.html