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  • New item   -64.12€Room temperature and humidity sensor with wall surface temperature measurement | 0…50°C | 0-100%rH | Modbus RTU | PoM 24VDC | RJ45 | IP30 | Sentera Controls | RWTHM-2
    New item   -64.12€Room temperature and humidity sensor with wall surface temperature measurement | 0…50°C | 0-100%rH | Modbus RTU | PoM 24VDC | RJ45 | IP30 | Sentera Controls | RWTHM-2 1
    New item   -64.12€Room temperature and humidity sensor with wall surface temperature measurement | 0…50°C | 0-100%rH | Modbus RTU | PoM 24VDC | RJ45 | IP30 | Sentera Controls | RWTHM-2 2
    New item   -64.12€Room temperature and humidity sensor with wall surface temperature measurement | 0…50°C | 0-100%rH | Modbus RTU | PoM 24VDC | RJ45 | IP30 | Sentera Controls | RWTHM-2 3
    New item   -64.12€Room temperature and humidity sensor with wall surface temperature measurement | 0…50°C | 0-100%rH | Modbus RTU | PoM 24VDC | RJ45 | IP30 | Sentera Controls | RWTHM-2 4
    New item   -64.12€Room temperature and humidity sensor with wall surface temperature measurement | 0…50°C | 0-100%rH | Modbus RTU | PoM 24VDC | RJ45 | IP30 | Sentera Controls | RWTHM-2 5

    Room temperature and humidity sensor with wall surface temperature measurement | 0…50°C | 0-100%rH | Modbus RTU | PoM 24VDC | RJ45 | IP30 | Sentera Controls | RWTHM-2

    Code: RWTHM-2
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  • Product description

    Room temperature and humidity sensor with wall surface temperature measurement | 0…50°C | 0-100%rH | Modbus RTU | PoM 24VDC | RJ45 | IP30 | Sentera Controls | RWTHM-2

    The RWTHM-2 is a Sentera Controls room temperature and humidity sensor with wall surface temperature measurement, measuring temperature (0…+50 °C) and relative humidity (0–100 % rH) in a room and the temperature on the wall surface. Data is transmitted digitally only, via Modbus RTU, and the 24 VDC power arrives over the same cable through the RJ45 connector (Power over Modbus, PoM). The second temperature sensor, on an aluminium plate in the rear cover, measures the surface temperature of the wall on which it is mounted – together with the air humidity this makes it possible to calculate the dew point and assess the risk of condensation on the wall.

    Key idea:
    One cable for both power and communication. The sensor is connected with a standard RJ45 cable to Sentera PoM devices or the Modbus network, so no separate power supply and no analog cables for each measuring point are needed – especially convenient when there are many sensors.
    Measurement
    0…+50 °C / 0–100 % rH
    Output
    Modbus RTU (RS485)
    Power supply
    24 VDC via Modbus (PoM), RJ45
    Protection
    IP30, indoors only

    Operating principle

    The sensor is fixed to the wall (2 holes of Ø 6 mm) so that the rear aluminum plate makes good contact with the wall surface, and is connected with a single RJ45 cable: 24 VDC, GND and Modbus RTU (A, /B) run in the same cable (PoM).

    Integrated digital sensors measure air temperature and relative humidity, and the second sensor measures wall surface temperature; the dew point is calculated. Measuring ranges are selected over Modbus RTU, and the values are provided in input registers (IR2 – temperature, IR11 – relative humidity); a controller, the BMS, a Sentera PoM device or SenteraWeb reads them, and the firmware is updated over the Modbus network.

    Result – not only the room air but also the wall surface is monitored: ventilation can be increased earlier, before condensate and mould start to accumulate on cold walls.

    Benefits RWTHM-2?
    Power and communication in one RJ45 cable – fewer wires, faster installation and no analog signal errors on long lines.

    Technical specifications

    Product type Room temperature and humidity sensor with wall surface temperature measurement
    Manufacturer / code Sentera Controls / RWTHM-2
    Measured quantities Air temperature, relative humidity, wall surface temperature, ambient illuminance; the dew point is calculated
    Temperature range 0…+50 °C (selectable via Modbus RTU)
    Humidity range 0–100 % rH, non-condensing
    Accuracy ±0.4 °C (0…+50 °C); ±3 % rH (0–100 %)
    Output Digital – Modbus RTU (RS485), no analog outputs
    Modbus registers IR2 – temperature, IR11 – relative humidity
    Supply voltage 24 VDC via Modbus (PoM)
    Energy usage 1.2 W, average 0.9 W, Imax 50 mA
    Connection RJ45 socket
    Indication Red / yellow / green LED, ambient light sensor
    Installation On a wall, 2 holes Ø 6 mm
    Protection class IP30 (EN 60529), indoor use only
    Operating conditions 0…+50 °C, 0–100 % rH non-condensing
    Weight 0.08 kg (net)
    Compliance EMC 2014/30/EU, WEEE 2012/19/EU, RoHS 2011/65/EU, LVD 2014/35/EU

    Manufacturer documentation

    ✔ Recommended by Elektrotechnikos sprendimai

    Original manufacturer documentation – technical data, wiring diagrams and installation instructions.

    Main functions

    • Wall surface temperature – a second sensor on an aluminium plate – for assessing the risk of condensation and mold.
    • Power over Modbus (PoM) – power and communication over a single RJ45 cable.
    • Modbus RTU – temperature and humidity in registers, ranges and parameters can be changed remotely.
    • Firmware update – over the Modbus RTU network.
    • Configuration – Configuration and monitoring – the free Sentera 3SModbus software (via the CNVT-USB-RS485 converter) or the Sensistant Modbus configurator.
    • LED indication – red – value out of range or sensor fault, yellow – danger zone, green – normal; blinking LEDs indicate Modbus data transmission.

    Where is it used?

    • Rooms with cold external walls
    • Basements, archives, warehouses
    • Buildings being renovated where condensation control is important
    • Residential rooms at risk of mould
    • BMS and SenteraWeb monitoring
    • Schools and kindergartens in old buildings
    • Museum and library storage rooms

    On-demand operation

    For building renovation engineers.
    Wall surface temperature and dew point show the risk of condensation at insulation or thermal bridge locations.
    For the archive and storage administrator.
    Dew point control allows ventilation to be increased in time, before mould appears on the walls.
    For Sentera PoM system integrators.
    A single RJ45 cable supplies both power and Modbus RTU, so no separate power supply is needed at the sensor.

    Practical application

    If the surface of an archive's exterior wall cools to the dew point of the air, then a controller or SenteraWeb that reads RWTHM-2 data over Modbus RTU can boost ventilation before condensation starts to build up on the wall.

    Application guide: how it is used in practice

    The RWTHM-2 adapts to different sites – only what reads its data changes:

    Site What is connected Result Installer's note
    Building with BMS RJ45 → Modbus RTU line with 24 VDC PoM power Temperature and humidity are monitored and archived centrally A separate Modbus address for each sensor
    Remote monitoring RJ45 → Sentera internet gateway → SenteraWeb Data log, graphs, internet alerts A Sentera internet gateway is required
    Sentera Modbus controller / speed controller RJ45 → Sentera device with Modbus and PoM Ventilation controlled according to the measured temperature or humidity Check that the device supplies PoM power
    Room with a cold external wall Mounted on the most problematic wall Ventilation is boosted as the wall temperature approaches the dew point The aluminium plate must make good contact with the wall

    How to choose a room temperature and humidity transmitter

    Installation / output / power supply Recommended model
    Wall, 3 analog outputs, 18–34 VDC, 4-wire RSTHF-3 (room transmitter, -F)
    Wall, 3 analog outputs, 18–34 VDC or 15–24 VAC, 3-wire RSTHG-3 (room transmitter, -G)
    Wall, Modbus RTU only, PoM, RJ45 RSTHM-2 (room Modbus sensor)
    Wall, Modbus RTU + wall surface temperature (dew point control), PoM RWTHM-2 (with surface temperature sensor) ← this model
    Wall, direct control with 1 output, 18–34 VDC RCTHF-2 (smart room, -F)
    Wall, direct control with 1 output, 18–34 VDC or 15–24 VAC RCTHG-2 (smart room, -G)
    Wall, direct control with 1 output, 24 VDC via RJ45 (PoM) or terminals RCTHH-2 (smart room, PoM)
    Flush-mounted / surface-mounted, 1 output, powered directly from the 230 V mains FCTH8 (85–264 VAC)
    Flush-mounted / surface-mounted, 1 output, 18–34 VDC FCTHF (-F)
    Flush-mounted / surface-mounted, 1 output, 18–34 VDC or 15–24 VAC FCTHG (-G)
    Rule: first decide where the measurement is made (duct, room, outdoors), then what you need from the transmitter: separate analog signals for a controller (transmitter, 3 outputs), data only to a BMS (Modbus / PoM version), or direct fan control with a single output (smart sensor). Finally – the supply and number of wires: -F – 24 VDC, 4-wire, separate grounds; -G – AC or DC, 3-wire, common ground; -M / -H – power over the Modbus cable (RJ45).
    When to choose another solution: without surface temperature – RSTHM-2; for analog outputs – RSTHF-3 / RSTHG-3; outdoors – ODTHM.

    Pros

    • Power and communication via a single RJ45 cable
    • Accuracy ±0.4 °C, ±3 % rH
    • Ranges are selected via Modbus RTU
    • Firmware is updated via Modbus
    • Wall surface temperature measurement

    Cons / limitations

    • No analog outputs – a Modbus RTU controller or BMS is required
    • Powered only via PoM (24 VDC) – a device or power supply that provides PoM is required
    • IP30 – dry rooms only

    Safety and installation notes

    • Installation and connection are to be carried out by a qualified electrician / automation specialist with the power disconnected.
    • Power supply – only 24 VDC via Modbus (PoM); do not connect the RJ45 connector to computer network (Ethernet) equipment.
    • Resetting the Modbus communication parameters – with a jumper on PROG pins 1 and 2 for at least 5 s.
    • For indoor use only.

    Quick selection guide

    0…+50 °C
    0–100 % rH
    Modbus RTU
    PoM 24 VDC
    RJ45
    IP30
    Suitable when you need:
    • to measure temperature and humidity in a room and on a wall surface and pass them to a BMS;
    • to reduce cabling – power and communication over a single cable;
    • to monitor the risk of condensation on walls;
    Check before use:
    • whether the controller / BMS supports Modbus RTU;
    • whether the Modbus line supplies 24 VDC PoM power;
    • A Modbus address plan for all sensors.
    Important reminder: The RWTHM-2 has no analog outputs – data is obtained only via Modbus RTU.

    FAQ

    Is there a 0-10 V output?
    No, the sensor has Modbus RTU only; for analog outputs choose RSTHF-3 or RSTHG-3.
    What is PoM?
    Power over Modbus – 24 VDC power is supplied over the same RJ45 cable as the Modbus RTU communication.
    Can the measuring range be changed?
    Yes, via Modbus RTU using the 3SModbus software or a BMS.
    How do I reset the Modbus settings?
    With a jumper on PROG contacts 1 and 2 for at least 5 seconds.
    What is the surface sensor for?
    It measures the wall temperature, which, compared with the dew point of the air, allows ventilation to be boosted in time and condensation to be avoided.
    How do I mount the sensor?
    On a wall through 2 holes of Ø 6 mm, so that the rear aluminum plate makes good contact with the wall surface.

    Room temperature and humidity sensor with wall surface temperature measurement | 0…50°C | 0-100%rH | Modbus RTU | PoM 24VDC | RJ45 | IP30 | Sentera Controls | RWTHM-2

    Sentera RWTHM-2 – room temperature and humidity sensor with wall surface temperature measurement: 0…+50 °C, 0–100 % rH, Modbus RTU and 24 VDC supply via RJ45 (PoM), IP30. Suitable for BMS and SenteraWeb ventilation automation.

    Illustrative image may have been created using AI. The appearance of the product may differ slightly from the image shown. Please refer to the technical specification.

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