Systemair SAVE VTR
Controls and monitors Systemair SAVE VTR ventilation systems via Modbus RTU
This template connects Systemair SAVE VTR ventilation units (VTR500L, VTR300, VTR700, VTR250) to ModbusCloud via Modbus RTU. It reads sensor values, fan speeds, alarm status, and filter remaining time, and allows control of temperature setpoint, user mode, and airflow levels.
- Protocol
- Modbus RTU
- Connection
- RS485, 19200 baud
- Registers
- 17, read and write
- Brand
- Systemair
- Key readings
- Supply air temperature · Outdoor air temperature · Exhaust air temperature · Supply and exhaust fan speed · Relative humidity · Heat exchanger output · Alarm status · Filter remaining time
- Available commands
- Temperature setpoint · User mode · Manual supply airflow level · Manual exhaust airflow level
- Compatible models
- VTR500L · VTR300 · VTR700 · VTR250 · SAVE VTR
- Last updated
Registers (17)
13 read, 4 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| REG_USERMODE_MODE | Read | ||||
| REG_SENSOR_SAT | °C | Read | |||
| REG_SENSOR_RHS_PDM | % | Read | |||
| REG_SENSOR_PDM_EAT_VALUE | °C | Read | |||
| REG_OUTPUT_SAF | o/min | Read | |||
| REG_OUTPUT_EAF | o/min | Read | |||
| REG_OUTPUT_ALARM | Read | ||||
| REG_SENSOR_OAT | °C | Read | |||
| REG_HEAT_EXCHANGER_FROM_SATC | % | Read | |||
| REG_OUTPUT_Y2_ANALOG | W | Read | |||
| REG_OUTPUT_Y2_DIGITAL | Read | ||||
| REG_FILTER_REMAINING_TIME | Read | ||||
| REG_FILTER_REMAINING_TIME | h | Read | |||
| REG_TC_SP | °C | Write | |||
| REG_USERMODE_HMI_CHANGE_REQUEST | Write | ||||
| REG_USERMODE_MANUAL_AIRFLOW_ LEVEL_SAF | % | Write | |||
| REG_USERMODE_MANUAL_AIRFLOW_ LEVEL_EAF | % | Write |
Loading registers…
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If a device is not in the library yet, we build the template for free as soon as we have the register data.
Use cases
- Monitor supply, exhaust, and outdoor air temperatures on a live dashboard to verify ventilation performance.
- Create an alert when a filter replacement is due based on the filter remaining time register.
- Adjust the temperature setpoint remotely to match seasonal changes without a site visit.
- Switch the user mode between away, normal, and boost to optimize energy use across multiple buildings.
- Set up alarm notifications for fault conditions so you can respond before tenants report issues.
- Track heat exchanger output over time to detect degradation and schedule preventive maintenance.
Installation
Connect the ModbusCloud gateway to the Systemair SAVE VTR Connection Board using three wires: A, B, and GND on the RS485 terminals.
Set the Modbus slave address on the SAVE VTR unit to a unique value between 1 and 247, and configure the baud rate to 19200 with even parity.
In the ModbusCloud portal, assign the same slave address and communication settings (19200 baud, even parity) to the gateway channel.
Import the Systemair SAVE VTR template from the ModbusCloud template library and link it to the configured device.
Verify the connection by checking that live sensor readings such as supply air temperature and fan speed appear on the dashboard.
If multiple VTR units share the same RS485 bus, ensure each unit has a unique slave address and proper bus termination.
Things to watch for
I get no response from the SAVE VTR unit after wiring the RS485 connection. What should I check?
Verify that you are using the correct terminals (A, B, and GND) on the Connection Board. Confirm the slave address, baud rate (19200), and parity (even) match between the device and the ModbusCloud gateway. Swapping the A and B wires is a common fix if polarity is reversed.
The filter remaining time shows an incorrect or very large value. Why?
Filter remaining time is stored across two consecutive registers (7004 and 7005). Make sure the template is reading both registers. If you see unexpected values, verify the register order and byte/word order settings in the gateway configuration.
Can I use a different baud rate than 19200?
Yes. The Systemair SAVE VTR supports baud rates from 9600 to 115200. Change the baud rate on both the device and the ModbusCloud gateway to match. The template default is 19200 with even parity.
Can I connect multiple SAVE VTR units on one RS485 bus?
Yes, as long as each unit has a unique Modbus slave address. Use proper RS485 daisy-chain wiring with termination resistors at both ends of the bus if cable runs are long.
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