I’ve recently purchased a modbus RS485-to-TCP interface from Aliexpress, to control my Systemair SAVE VSR300 ventilation unit from Home Assistant. And after a bit of fiddling I got it up and running, and was able to read back values manually using QModMaster.
But after adding some modbus sensors to Home Assistant, it seems that the values aren’t what I would expect, as if the register is wrong. I add a modbus sensor for the outside air temperature register, and I get what seems to be the regulated indoor air temperature.
The same goes for other modbus sensors I’ve added:
- platform: modbus
scan_interval: 5
registers:
- name: Temperature setpoint, supply air
hub: systemair_vsr300
unit_of_measurement: °C
slave: 1
register: 2054
register_type: input
data_type: int
scale: 0.1
- name: Usermode, active
hub: systemair_vsr300
slave: 1
register: 1161
register_type: input
data_type: int
- name: Temperature, outdoor air
hub: systemair_vsr300
unit_of_measurement: °C
slave: 1
register: 12102
register_type: input
data_type: int
scale: 0.1
- name: Temperature, supply air
hub: systemair_vsr300
unit_of_measurement: °C
slave: 1
register: 12103
register_type: input
data_type: int
scale: 0.1
I’ve been in touch with Systemair, and I know that this is the correct modbus register overview.
The strange thing is that if I connect to the modbus interface with QModMaster and start reading out values, I get the expected value (or I sometime get Invalid data or Timeout). But I never get the value of what seems to be a different register. But I also see that if I start reading values with QModMaster, Home Assistant seems to start showing the correct value also.
Anybody that has an idea of what’s going on here?