Modbus set value holding register

Hi. I have struggled with this a long time. I have a ventilationsystem with modbus and most of the functions works well with Homeassistant but i have problem when I am trying to set fan speed.

There is no logic how the ventilation system responds to the commands. Before I went over I used Homeseer and there it worked fine. I have made two sliders for the exhaust and supply fan with value from 0-100.

for example if I change the slider from 30 to 70 the fan speed can decrease?

attach some configs

I am facing similar issue, have you been able to solve it?