Modbus: no polling?

I have devices connected via modbus TCP. Turning on/off lights works fine. But when a light is turned on via other means, HASS does not detect this (remains off). Seems the system is not polling the modbus registers. Any clue?

Config:

modbus:
  - name: "hub1"
    type: tcp
    host: 192.168.1.17
    port: 502
    lights:
        - name: "luster_living"
          slave: 1
          address: 816

Default scan interval is 10 seconds. Is there no change after that time?

Indeed, no change at all

What kind of device is it? And how do you normaly send on/off via the modbus?

Device is SH2WEB24 from Carlo Gavazzi

The “other” way to turn on/off the lights is via wall monostable push buttons.