Senzomatic FHT-I
Detects floor flooding while monitoring temperature and humidity in interiors.
The Senzomatic FHT-I is a Modbus RTU flood detection sensor designed for interior use. It reads floor flooding status, ambient temperature, relative and absolute humidity, dew point, and power supply voltage. A sensing cable laid on the floor detects water leakage in utility rooms, kitchens, and similar areas.
- Protocol
- Modbus RTU
- Connection
- RS485, 19200 baud
- Registers
- 9, read only
- Brand
- Senzomatic
- Key readings
- Temperature · Relative humidity · Dew point temperature · Absolute humidity · Power supply voltage · Flood counter
- Compatible models
- FHT-I
- Last updated
Registers (9)
9 read, 0 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| 8 - 7 Temperature | °C | Read | |||
| 8 - 7 Relative humidity | % | Read | |||
| 8 - 7 Dew point temperature | °C | Read | |||
| 8 - 7 Absolute humidity | g/m³ | Read | |||
| 8 - 7 Power supply voltage | V | Read | |||
| 8 - 7 Flood counter | count | Read | |||
| 8 - 7 Flood resistance positive ticks avg | V | Read | |||
| 8 - 7 Flood resistance negative ticks avg | V | Read | |||
| 8 - 7 X - The Last Message after reading | Read |
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Use cases
- Monitor flood detection status across multiple rooms from a single cloud dashboard.
- Create an alert when the flood counter increments to notify building owners of a water leak immediately.
- Track ambient temperature and relative humidity trends in utility rooms to detect early signs of moisture problems.
- Log dew point temperature over time to identify condensation risks in basements or storage areas.
- Monitor power supply voltage of each FHT-I sensor to detect wiring or power issues before they cause downtime.
- Combine flood sensor data with a water valve actuator workflow to shut off the main supply on leak detection.
Installation
Lay the FHT-I sensing cable flat on the floor in the target area, such as behind a washing machine or under a kitchen cabinet.
Wire the FHT-I to the RS-485 bus of your ModbusCloud Gateway, connecting A, B, and GND terminals correctly.
Set the Modbus slave address on the FHT-I to a unique value that does not conflict with other devices on the bus.
Configure the gateway RS-485 port for 19200 baud, 8 data bits, odd parity, and 1 stop bit to match the FHT-I defaults.
Import the Senzomatic FHT-I template from the ModbusCloud library and assign it to the correct gateway and slave address.
Verify that live readings for temperature, humidity, and flood counter appear on the ModbusCloud dashboard before leaving the site.
Things to watch for
I see incorrect or garbled readings for temperature and humidity. What could be wrong?
All FHT-I registers are float32 with big-endian word swap (byte order 8-7). Make sure your gateway is configured for this byte order. A mismatch will produce nonsensical values.
Can I use the humidity-based early leak detection in a bathroom?
No. Senzomatic advises against enabling humidity-based leak detection in areas where humidity naturally rises and falls repeatedly, such as bathrooms. The rapid humidity changes will cause false alerts.
The sensor does not respond on the Modbus bus. What should I check?
Verify that the baud rate is set to 19200 with odd parity (8E1) on both the sensor and the gateway. Also confirm that the A and B RS-485 lines are not swapped and that the slave address matches the template configuration.
Is a bus termination resistor required for the FHT-I?
If the FHT-I is at the end of a long RS-485 bus run, add a 120 ohm termination resistor across the A and B lines. For short cable runs with only a few devices, termination is usually not necessary but recommended for reliability.
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