Sentera RSTHF-3
Room sensor for temperature, humidity and light with three outputs for ventilation control.
The Sentera RSTHF-3 is a room sensor that measures temperature, relative humidity and ambient light and drives ventilation equipment through three analogue outputs. This Modbus RTU template reads temperature, humidity, dew point, light level and alarm flags and lets you set alert limits and override the outputs from ModbusCloud.
- Protocol
- Modbus RTU
- Connection
- RS485, 19200 baud
- Registers
- 67, read and write
- Brand
- Sentera
- Key readings
- Temperature · Relative humidity · Dew point · Ambient light · Output values · Sensor alarms
- Available commands
- Alert limits · Output override · Output type · Light levels for active and standby · LED brightness
- Compatible models
- RSTHF-3 · RSTHG-3 · RSTHH-3
- Last updated
Registers (67)
67 read, 45 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| Temperature | °C | Read | |||
| Relative Humidity | %RH | Read | |||
| Dew Point | °C | Read | |||
| Ambient Light | lux | Read | |||
| Active Standby State | Read | ||||
| Output Value Ao1 | % | Read | |||
| Output Value Ao2 | % | Read | |||
| Output Value Ao3 | % | Read | |||
| Temperature Alert Flag 1 | Read | ||||
| Temperature Range Limit Flag 1 | Read | ||||
| Temperature Sensor State | Read | ||||
| Temperature Alert Flag 2 | Read | ||||
| Temperature Range Limit Flag 2 | Read | ||||
| Humidity Alert Flag 1 | Read | ||||
| Humidity Range Limit Flag 1 | Read | ||||
| Humidity Sensor State | Read | ||||
| Humidity Alert Flag 2 | Read | ||||
| Humidity Range Limit Flag 2 | Read | ||||
| Ambient Light Sensor State | Read | ||||
| Minimum Temperature Alert 1 | °C | Read and write | |||
| Maximum Temperature Alert 1 | °C | Read and write | |||
| Minimum Humidity Alert 1 | %RH | Read and write | |||
| Maximum Humidity Alert 1 | %RH | Read and write | |||
| Minimum Temperature Alert 2 | °C | Read and write | |||
| Maximum Temperature Alert 2 | °C | Read and write | |||
| Minimum Humidity Alert 2 | %RH | Read and write | |||
| Maximum Humidity Alert 2 | %RH | Read and write | |||
| Minimum Temperature Range 1 | °C | Read and write | |||
| Maximum Temperature Range 1 | °C | Read and write | |||
| Minimum Temperature Range 2 | °C | Read and write | |||
| Maximum Temperature Range 2 | °C | Read and write | |||
| Minimum Humidity Range 1 | %RH | Read and write | |||
| Maximum Humidity Range 1 | %RH | Read and write | |||
| Minimum Humidity Range 2 | %RH | Read and write | |||
| Maximum Humidity Range 2 | %RH | Read and write | |||
| Active Mode Light Level | lux | Read and write | |||
| Standby Mode Light Level | lux | Read and write | |||
| Output Type Ao1 | Read and write | ||||
| Output Overwrite Enable Ao1 | Read and write | ||||
| Output Overwrite Value Ao1 | % | Read and write | |||
| PWM Voltage Source Ao1 | Read and write | ||||
| Output Minimum Ao1 | % | Read and write | |||
| Output Maximum Ao1 | % | Read and write | |||
| Output Type Ao2 | Read and write | ||||
| Output Overwrite Enable Ao2 | Read and write | ||||
| Output Overwrite Value Ao2 | % | Read and write | |||
| PWM Voltage Source Ao2 | Read and write | ||||
| Output Minimum Ao2 | % | Read and write | |||
| Output Maximum Ao2 | % | Read and write | |||
| Output Type Ao3 | Read and write | ||||
| Output Overwrite Enable Ao3 | Read and write | ||||
| Output Overwrite Value Ao3 | % | Read and write | |||
| PWM Voltage Source Ao3 | Read and write | ||||
| Output Minimum Ao3 | % | Read and write | |||
| Output Maximum Ao3 | % | Read and write | |||
| Output Ao3 Measurement | Read and write | ||||
| LED Indication | Read and write | ||||
| LED Brightness | % | Read and write | |||
| Modbus Address | Read and write | ||||
| Modbus Baud Rate | Read and write | ||||
| Modbus Parity | Read and write | ||||
| Modbus Safety Timeout | min | Read and write | |||
| Network Termination | Read and write | ||||
| Modbus Registers Reset | Read and write | ||||
| Device Type | Read | ||||
| Hardware Version | Read | ||||
| Firmware Version | Read |
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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
- Show temperature, humidity and dew point per room on a ModbusCloud dashboard.
- Get an email when humidity in a room stays above the alert limit or a sensor reports a problem.
- Compare room occupancy from the light level with the ventilation output over 365 days of history.
- Adjust the alert limits for a room remotely when its use changes.
- Override an output from the portal during commissioning to test a fan or damper.
Installation
Connect VIN, GND, A and /B to the sensor and run the RS485 bus to the ModbusCloud Gateway.
Switch on the built-in termination on the last device of the line and terminate the other end at the Gateway.
Give every Sentera device on the bus its own address; the factory default is address 1 at 19200 baud, 8E1.
In ModbusCloud, add a Modbus device with that address and settings and import the Sentera RSTHF-3 template.
Check that temperature, humidity and light level match the room.
Things to watch for
The sensor does not answer on the bus. What should I check?
Check the supply, A and /B, and that address, baud rate and parity in ModbusCloud match the sensor. The factory setting is address 1, 19200 baud, 8E1. New Sentera devices all start at address 1, so connect them one at a time and give each its own address first.
Why does the light state stay on Low light intensity?
The sensor reports Active above the active light level and Standby below the standby level. Between the two it reports low light intensity. Set the two levels to match the room, for example 100 lux and 10 lux.
The output does not follow the value I write. Why?
An override value only works when override is enabled for that output. Set the enable register to 1 first, then write the value, and set it back to 0 afterwards. When the Modbus safety timeout runs out without traffic, the outputs go to 0.
What should I watch out for when writing settings?
A new address, baud rate or parity takes effect on the sensor, so update the Modbus device in ModbusCloud right after. Writing 1 to the register reset restores all holding registers above 10 to their defaults, including alert limits and output settings.
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