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  • New item   -38.13€Room temperature and humidity sensor | 0…50°C | 0-100%rH | Modbus RTU | PoM 24VDC | RJ45 | IP30 | Sentera Controls | RSTHM-2
    New item   -38.13€Room temperature and humidity sensor | 0…50°C | 0-100%rH | Modbus RTU | PoM 24VDC | RJ45 | IP30 | Sentera Controls | RSTHM-2 1
    New item   -38.13€Room temperature and humidity sensor | 0…50°C | 0-100%rH | Modbus RTU | PoM 24VDC | RJ45 | IP30 | Sentera Controls | RSTHM-2 2
    New item   -38.13€Room temperature and humidity sensor | 0…50°C | 0-100%rH | Modbus RTU | PoM 24VDC | RJ45 | IP30 | Sentera Controls | RSTHM-2 3
    New item   -38.13€Room temperature and humidity sensor | 0…50°C | 0-100%rH | Modbus RTU | PoM 24VDC | RJ45 | IP30 | Sentera Controls | RSTHM-2 4

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

    Code: RSTHM-2
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  • Product description

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

    The RSTHM-2 is a Sentera Controls room temperature and humidity sensor that measures temperature (0…+50 °C) and relative humidity (0–100 % rH) in a room. 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). It additionally has an ambient light sensor and a three-colour LED indication.

    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 a wall in the room (2 holes of Ø 6 mm), away from heat sources and drafts, 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; 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 uses them to control ventilation, humidification or heating; the firmware is updated over the Modbus network.

    Result – microclimate data of each room in the BMS, while the LED on site shows whether the values are within normal limits.

    Benefits RSTHM-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
    Manufacturer / code Sentera Controls / RSTHM-2
    Measured quantities Temperature, relative humidity, ambient illuminance
    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 0.312 W, average 0.234 W, Imax 13 mA
    Connection RJ45 (1 – 24 VDC, 3 – A, 5 – /B, 7 – GND)
    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 0.075 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

    • 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?

    • Offices, classrooms, meeting rooms
    • Residential rooms
    • Hotels, healthcare facilities
    • BMS systems with many rooms
    • Sentera PoM and SenteraWeb solutions
    • Student dormitories and apartments in apartment buildings with centralized ventilation
    • Laboratory and training institution rooms

    On-demand operation

    For the office building BMS integrator.
    Many room sensors connect to a single Modbus RTU line, and temperature and humidity are read from fixed registers.
    For Sentera PoM system installers.
    A single RJ45 cable supplies power and communication, so no 24 V power supply unit is needed in the room.
    For hotel maintenance managers.
    The on-site LED indication shows whether the microclimate is within normal limits, without connecting to the system.

    Practical application

    If in an office building the temperature and humidity of each of 20 offices have to be monitored in the BMS, then the RSTHM-2 units are connected to the Modbus RTU network with RJ45 cables, each is assigned a separate address, and the values are read from IR2 and IR11.

    Application guide: how it is used in practice

    The RSTHM-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

    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) ← this model
    Wall, Modbus RTU + wall surface temperature (dew point control), PoM RWTHM-2 (with surface temperature sensor)
    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: for analog outputs – RSTHF-3 / RSTHG-3; for wall surface temperature – RWTHM-2; for direct control – RCTH-2 series; for a duct – DSTHM-2.

    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
    • LED indication and light sensor

    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 pass them to a BMS;
    • to reduce cabling – power and communication over a single cable;
    • to monitor many rooms on a single Modbus line;
    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 RSTHM-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.
    Is it suitable for damp rooms?
    No, the IP30 enclosure is for dry rooms only.
    How much power does the sensor use?
    Up to 0.312 W (0.234 W on average), Imax 13 mA.

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

    Sentera RSTHM-2 – room temperature and humidity sensor: 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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