@Dmytro said in Error: "Write of group with index 3 skipped": Write Only On Change || False In a previous post was a mistake. Write Only On Change || True It causes error "Write of group with index 3 skipped" If that parameter has value False, error message in Port monitor disappears. Instead of that, Port monitor shows to me another problem: 15.12.2021 14:37:40.0122 => Send: 240 16 6 3 0 1 2 3 0 201 7 15.12.2021 14:37:40.0822 Timeout 15.12.2021 14:37:40.0922 => Send: 240 16 6 3 0 1 2 3 0 201 7 15.12.2021 14:37:40.1622 Timeout 15.12.2021 14:37:40.1722 => Send: 240 16 6 3 0 1 2 3 0 201 7 15.12.2021 14:37:40.2422 Timeout 15.12.2021 14:37:40.2672 => Send: 240 3 0 0 0 66 208 218 15.12.2021 14:37:40.3372 Timeout 15.12.2021 14:37:40.3472 => Send: 240 3 0 0 0 66 208 218 15.12.2021 14:37:40.3652 <= Recv: 240 16 6 3 0 15.12.2021 14:37:40.3722 <= Recv: 1 228 96 15.12.2021 14:37:40.3722 Timeout So I still cannot write the value to the register.