Xvent
Monitors and controls ventilation units with heat and moisture recovery
This template connects Xvent ventilation units (Xroom, Xhouse, Xflat) via Modbus RTU. It reads CO2, humidity, temperatures, and airflow data, and allows control of fan speed, boost mode, summer mode, and setpoints.
- Protocol
- Modbus RTU
- Connection
- RS485, 19200 baud
- Registers
- 45, read and write
- Brand
- Xvent
- Key readings
- CO2 level (ppm) · Relative humidity (%RH) · Room temperature · Exhaust temperature · Actual airflow (m³/h) · Filter elapsed time (h)
- Available commands
- CO2 and RH setpoints · Boost mode duration and fan speed · Summer mode duration · Filter lifetime setting
- Compatible models
- Xroom · Xhouse · Xflat
- Last updated
Registers (45)
42 read, 11 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| FW version | Read | ||||
| act_state 1 | Read | ||||
| act_state 2 | Read | ||||
| act_state 3 | Read | ||||
| AQS_state | Read | ||||
| AQS_state.fan_flow | m³/h | Read | |||
| set_FAN_FLOW | m³/h | Read | |||
| act_PID.prop | mV | Read | |||
| act_PID.integ | mV | Read | |||
| act_PID.der | mV | Read | |||
| act_PID.result | Read | ||||
| set_FAN_SPEED | V | Read | |||
| set_T_ROOM | °C | Read | |||
| act_CO2 | ppm | Read | |||
| act_RH | %RH | Read | |||
| act_Flow | m³/h | Read | |||
| act_T_ROOM | °C | Read | |||
| act_T_EXHAUST | °C | Read | |||
| FAN1.act_AO | V | Read | |||
| FAN1.act_tacho | rpm | Read | |||
| FAN2.act_AO | V | Read | |||
| FAN2.act_tacho | rpm | Read | |||
| timer.act_cool_preheat | s | Read | |||
| timer.act_cool_postheat | s | Read | |||
| timer.act_summer_mode | s | Read | |||
| timer.act_boost_mode | s | Read | |||
| timers_1 | s | Read | |||
| timers_2 | s | Read | |||
| act_FILTER_ELAPSED_TIME | h | Read | |||
| act_ui_timer | s | Read | |||
| act_preheat_timer High | s | Read | |||
| act_preheat_timer Low | s | Read | |||
| act_startup_timer | s | Read | |||
| rele | Read | ||||
| front panel | Read and write | ||||
| set_CO2 | ppm | Read and write | |||
| set_RH | % | Read and write | |||
| bits | Read and write | ||||
| corr_T_ROOM | °C | Read and write | |||
| set_BOOST_MODE_DURATION | s | Read and write | |||
| set_FILTER_LIFETIME | h | Read and write | |||
| set_SUMMER_MODE_DURATION | s | Read and write | |||
| set_BOOST_MODE_FAN_SPEED | % | Write | |||
| set_BOOST_MODE_FAN_FLOW | % | Write | |||
| set_FAN_OFFSET_STATIC | Pa | Write |
Loading registers…
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Use cases
- Monitor CO2 levels and relative humidity on a live dashboard to verify indoor air quality for your customer.
- Create alerts when filter elapsed time approaches the configured filter lifetime to schedule timely replacements.
- Adjust CO2 and RH setpoints remotely from the ModbusCloud platform without a site visit.
- Activate boost mode and set fan speed during high occupancy periods via the cloud interface.
- Track exhaust temperature and airflow trends over time to verify heat recovery performance.
- Enable summer mode remotely during warm periods to manage bypass operation and comfort.
Installation
Connect the ModbusCloud Gateway to the Xvent unit using a shielded RS-485 cable, wiring A to A and B to B terminals.
Set the Modbus RTU baud rate on the gateway to 19200 with odd parity (8E1) to match the Xvent default communication settings.
Configure a unique Modbus slave address on the Xvent unit and enter the same address in the ModbusCloud gateway configuration.
Import the Xvent template from the ModbusCloud template library and assign it to the configured Modbus device.
Verify communication by checking live values for CO2, humidity, and temperature on the ModbusCloud dashboard.
If multiple Xvent units share the same RS-485 bus, assign each unit a different slave address and add a separate device entry for each.
Things to watch for
The gateway cannot communicate with the Xvent unit. What should I check first?
Verify that the baud rate is set to 19200 and parity is set to odd (8E1) on both the gateway and the Xvent unit. Also confirm correct RS-485 wiring polarity (A to A, B to B).
Some registers return zero values even though sensors are connected. Why?
CO2 and RH sensors are optional accessories on Xvent units. If the corresponding sensor is not physically connected to the unit, those registers will return zero or default values.
Can I use this template for all Xvent models?
Yes. The template is compatible with the Xroom, Xhouse, and Xflat models. The register map is shared across these units.
Which registers are writable for remote control?
Holding registers 40000 to 40002, 40016 to 40018, 40021, and 40023 are writable. These cover CO2 and RH setpoints, boost mode settings, summer mode duration, and filter lifetime configuration.
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