Since state_class I got this error:
Logger: homeassistant.setup
Source: setup.py:179
First occurred: 01:14:59 (1 occurrences)
Last logged: 01:14:59
Setup failed for modbus: Unable to import component: cannot import name 'CONF_STATE_CLASS' from 'homeassistant.components.sensor' (/usr/src/homeassistant/homeassistant/components/sensor/__init__.py)
Just copied modbus folder, no modifications
Thanks