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  • New item   -66€Digital input/output module | Modbus RTU | 4DI + 2 relays 2A | 24VDC PoM | DIN rail | IP30 | Sentera Controls | DIO-M-R2
    New item   -66€Digital input/output module | Modbus RTU | 4DI + 2 relays 2A | 24VDC PoM | DIN rail | IP30 | Sentera Controls | DIO-M-R2 1
    New item   -66€Digital input/output module | Modbus RTU | 4DI + 2 relays 2A | 24VDC PoM | DIN rail | IP30 | Sentera Controls | DIO-M-R2 2
    New item   -66€Digital input/output module | Modbus RTU | 4DI + 2 relays 2A | 24VDC PoM | DIN rail | IP30 | Sentera Controls | DIO-M-R2 3
    New item   -66€Digital input/output module | Modbus RTU | 4DI + 2 relays 2A | 24VDC PoM | DIN rail | IP30 | Sentera Controls | DIO-M-R2 4

    Digital input/output module | Modbus RTU | 4DI + 2 relays 2A | 24VDC PoM | DIN rail | IP30 | Sentera Controls | DIO-M-R2

    Code: DIO-M-R2
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  • Product description

    Digital input/output module | Modbus RTU | 4DI + 2 relays 2A | 24VDC PoM | DIN rail | IP30 | Sentera Controls | DIO-M-R2

    DIO-M-R2 – a Sentera Controls DIN rail digital input / output module for a Modbus RTU network: 4 digital inputs with tacho function and 2 changeover (C/O) relay outputs. It allows devices without Modbus to be connected to the Sentera Modbus network.

    Key idea:
    The relays allow a pump, damper, heater or alarm to be switched on directly from Modbus, while the inputs read contacts and the fan tacho signal.
    Inputs
    4 DI (0–45 VDC), tacho
    Outputs
    2 C/O relays, 2 A / 250 VAC
    Power supply
    24 VDC PoM, Imax 60 mA
    Installation / protection
    DIN rail, IP30

    Operating principle

    The module is mounted on a 35 mm DIN rail and plugged into the Modbus RTU line via an RJ45 connector (1–2 +24 VDC, 3–4 A, 5–6 /B, 7–8 GND), through which it also receives 24 VDC power (Power over Modbus, max. 60 mA). Contacts or signals are connected to inputs DI1–DI4, and the controlled devices to the outputs.

    The digital inputs operate in the 0–45 VDC range (logic level 1.6 VDC, 100 kΩ), a 5 VDC output (≤100 mA) is provided for activating dry contacts, and the tacho function measures 0–1000 Hz (0–60 000 rpm). Two changeover relay outputs NO/COM/NC switch up to 2 A, 220 VDC / 250 VAC (60 W / 125 VA, i.e. 0.5 A at 250 VAC), and in standalone mode the relays can follow the digital inputs without a main controller.

    Result – input states and measurements become Modbus registers, and registers become output states, so non-Modbus equipment is integrated into a Sentera or BMS system. Configured with the 3SModbus software or Sensistant, the firmware is updated via Modbus RTU (bootloader); the LED in the RJ45 socket shows power and communication.

    Benefits DIO-M-R2?
    Non-Modbus equipment – contacts, signalling, pumps or dampers via relays – is connected to the Modbus system without an additional PLC.

    Technical specifications

    Product type Digital I/O module Modbus RTU
    Manufacturer / code Sentera Controls / DIO-M-R2
    Series DIO-M-D4 / DIO-M-R2
    Power supply 24 VDC via Modbus (PoM), RJ45, max. 60 mA
    Digital inputs 4 (DI1–DI4), 0–45 VDC, logic level 1.6 VDC, 100 kΩ
    Tacho function 0–1000 Hz (0–60 000 rpm)
    Relay outputs 2 × C/O (NO1/COM1/NC1, NO2/COM2/NC2)
    Relay load max. 2 A; 220 VDC / 250 VAC; 60 W / 125 VA (0.5 A at 250 VAC)
    Standalone mode Relays controlled by digital inputs
    5 VDC output ≤100 mA in total with the digital outputs (for dry contacts)
    Communication Modbus RTU (RS485), RJ45: 1–2 +24 VDC, 3–4 A, 5–6 /B, 7–8 GND
    Configuration 3SModbus, Sensistant; update via Modbus RTU (bootloader)
    Indication LED on the RJ45 socket: power and Modbus communication
    Installation 35 mm DIN rail, bottom latch
    Housing ABS, grey RAL 7035
    Protection class IP30 (EN 60529)
    Operating environment -10…+60 °C, 5–85 % rH non-condensing
    Weight 0.076 kg net
    Compliance LVD 2014/35/EU, EMC 2014/30/EU (EN 61000-6-1, -6-2, -6-3), WEEE, RoHS

    Manufacturer documentation

    ✔ Recommended by Elektrotechnikos sprendimai

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

    Main functions

    • 4 digital inputs – states of contacts, alarms and door switches – to Modbus.
    • Tacho measurement – fan speed monitoring 0–60 000 rpm.
    • 2 changeover relays – for switching on a pump, damper, heater or alarm (up to 2 A).
    • Standalone mode – the relays can follow the inputs without a master controller.
    • 5 VDC for dry contacts – no additional power supply is needed for input contacts.
    • Power over Modbus – 24 VDC and data over a single cable.
    • Update via Modbus RTU – the firmware is updated over the network (bootloader), configuration – 3SModbus or Sensistant.

    Where is it used?

    • Connecting non-Modbus equipment to a Sentera Modbus network
    • Fan speed (tacho) monitoring
    • Reading fire alarm, door and alarm contacts
    • Switching pumps, dampers and heaters via relays
    • General alarm signal
    • Switching on a water heater circulation pump by a BMS command
    • Stopping fans by a fire alarm contact in standalone mode

    On-demand operation

    For ventilation system commissioning engineers.
    The relay switches a pump or damper, and the tacho input confirms that the fan is rotating.
    For fire alarm interface installers.
    In standalone mode, a fire alarm contact switches the relay directly.
    For building administrators.
    Door, alarm and equipment statuses are visible to the BMS via Modbus registers.

    Practical application

    If the circulation pump of a water-based heater (up to 0.5 A at 250 VAC) has to start on a BMS command and fan rotation has to be confirmed, then the NO1/COM1 relay of the DIO-M-R2 switches the pump directly, and the tacho input returns the fan speed (up to 60 000 rpm) to a Modbus register.

    Application guide: how it is used in practice

    The DIO-M-R2 connects non-Modbus equipment to the Modbus network – only the connected signals change:

    Site What is connected Result Installer's note
    Air handling unit Fan tacho output → DI1 Speed (rpm) is visible to the BMS, a stoppage can be detected Tacho up to 1000 Hz
    Fire alarm / emergency stop Dry contact → DI2 + 5 VDC Contact status is transmitted via Modbus Use 5 VDC for dry contacts only
    Pump or heater Contactor coil → relay NO/COM Switching on by a Modbus command Relay load up to 2 A; for a higher load – via a contactor
    Air damper Damper actuator power supply → relay 2 The damper opens together with the fan In standalone mode the relay can be controlled by the input

    How to choose an I/O module

    Required inputs / outputs Recommended model
    4 digital inputs + 4 digital outputs (5 VDC) DIO-M-D4 (4 DI + 4 DO, PWM measurement)
    4 digital inputs + 2 changeover relays DIO-M-R2 (4 DI + 2 C/O relays 2 A) ← this model
    Rule: if you need to switch a load directly (pump, damper, heater contactor) – DIO-M-R2 with relays; if 5 VDC logic signals are enough and you need more outputs and PWM measurement – DIO-M-D4.
    When to choose another solution: for analog signals – DADCM-08 / DADCM-44 (inputs) and DDACM-03 / DDACM-I3 / MDACM1 (outputs).

    Pros

    • 4 digital inputs with tacho
    • Power over Modbus (PoM)
    • 5 VDC for dry contacts
    • Update via Modbus RTU
    • DIN rail
    • 2 changeover relays
    • Standalone mode

    Cons / limitations

    • IP30 – in a panel / indoors only
    • No analog inputs / outputs – use DADCM-08 / DDACM-03 for that
    • Relays up to 2 A at 250 VAC – up to 125 VA; larger loads require a contactor
    • Only 2 outputs

    Safety and installation notes

    • Installation and connection are to be carried out by a qualified electrician or automation specialist with the power disconnected.
    • Use the 5 VDC output for dry contacts only; total 5 VDC load ≤100 mA.
    • Do not exceed the relay limits: 2 A, 220 VDC / 250 VAC, 60 W / 125 VA; 230 VAC circuits are to be connected by an electrician.
    • Do not exceed the power of the Power over Modbus (PoM) supply – add up the currents of all devices powered on the line.
    • Use at -10…+60 °C, 5–85 % rH, non-condensing.

    Quick selection guide

    Modbus RTU
    4 DI
    2 relays 2 A
    24 VDC PoM
    DIN
    IP30
    Suitable when you need:
    • to connect non-Modbus equipment to the Sentera Modbus network;
    • to read contacts and the fan tacho signal;
    • to switch a pump, damper or alarm via relays.
    Check before use:
    • how many and what kind of signals are needed;
    • the output load (relays up to 2 A);
    • the reserve of the PoM power supply.
    Important reminder: The DIO-M-R2 is not an analog module – for 0-10 VDC signals choose the DADCM / DDACM series.

    FAQ

    Can fan speed be measured?
    Yes, the tacho function measures 0–1000 Hz (0–60 000 rpm).
    Is a separate supply required?
    No, 24 VDC is supplied over Modbus (PoM), and the module draws up to 60 mA.
    Can a 230 VAC load be switched directly?
    Yes, but at 250 VAC the relay power is limited to 125 VA (0.5 A), so use a contactor for larger loads.
    What is standalone mode?
    This is a mode in which the relays are switched according to the digital inputs without a main Modbus controller.
    How do I connect a dry contact?
    The module's 5 VDC output (up to 100 mA in total) is used to activate the dry contact, so no additional power source is needed.
    What is the difference between DIO-M-D4 and DIO-M-R2?
    The DIO-M-D4 has four 5 VDC outputs and PWM measurement, while the DIO-M-R2 has two switching relays and a standalone mode.

    Digital input/output module | Modbus RTU | 4DI + 2 relays 2A | 24VDC PoM | DIN rail | IP30 | Sentera Controls | DIO-M-R2

    Sentera DIO-M-R2 – a Modbus RTU digital I/O module: 4 DI with tacho, 2 C/O relays 2 A, 24 VDC PoM, DIN rail, IP30 – for integrating non-Modbus equipment.

    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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