FCU-SCB226 Fan Coil Unit Control Board [cite_start]

Figure 1: General view of the FCU-SCB226 board [cite: 472, 538]

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    • Manual v1.0 | [cite_start]14.06.2023 [cite: 454]

    FCU-SCB226
    Fan Coil Unit Control Board

    01. Description

    [cite_start]

    The FCU-SCB226 control board is specifically designed for the remote control of 2/4-pipe fan coils via an RS-485 interface[cite: 477]. [cite_start]It functions as a slave device using the Modbus RTU protocol to communicate with central control and monitoring stations[cite: 482].

    [cite_start]

    This unit is ideal for home, hotel, and greenhouse automation, offering temperature measurement on two independent channels through external NTC 10k sensors[cite: 479, 483].

    02. Technical Specifications

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    Parameter [cite: 481][cite_start]Detail [cite: 481]
    Supply Voltage [cite: 480][cite_start]12-24V DC [cite: 480]
    Supply Current [cite: 480]Max. [cite_start]1.0A [cite: 480]
    Analog Inputs [cite: 480][cite_start]2 (for NTC 10k Thermistors) [cite: 480]
    Digital Inputs [cite: 480][cite_start]2 (Discrete) [cite: 480]
    Valve Relay Outputs [cite: 480][cite_start]2 [cite: 480]
    Fan Relay Outputs [cite: 480][cite_start]3 [cite: 480]
    RS485 Slave Ports [cite: 480][cite_start]1 [cite: 480]
    Operating Temperature [cite: 480][cite_start]-20/+70°C [cite: 480]

    03. Wiring & Connections

    Power Supply

    [cite_start]

    The board is powered by a 12-24V DC source using a 2-wire circuit (VDD and GND)[cite: 545]. [cite_start]Connection points are located at connector J8[cite: 540, 546].

    Analog & Digital Inputs

    [cite_start]

    The unit features two analog channels for temperature measurement using NTC-10K remote thermistors with 12-bit ADC accuracy[cite: 551, 553]. [cite_start]The pair of optically isolated digital inputs requires an external power source (DC 12V) and can be utilized as limit switches for motorized valves[cite: 485, 569].

    Relay Outputs

    [cite_start]

    There are 5 independent relays with NO contacts, each capable of switching 5.0A at 250VAC[cite: 576, 577]. [cite_start]These are organized into two functional groups[cite: 486]:

      [cite_start]
    • Valve Control (V1, VCOM, V2): For solenoid or motorized valves in hot and cold pipe configurations[cite: 578, 580].
      • [cite_start]
    • Fan Control (FCOM, LOW, MID, HIGH): For controlling fan motor speeds[cite: 578, 580].

    RS485 Communication

    [cite_start]

    The RS485 Slave interface uses terminals A and B[cite: 567]. [cite_start]A 120 Ohm bus terminator can be added by shorting the T terminal to the B terminal if the device is at the end of the bus[cite: 567].

    04. Connection Points Summary

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    Connector [cite: 539][cite_start]Description [cite: 539]
    J8 [cite: 540][cite_start]DC Power Supply (12-24V DC) [cite: 540]
    J7 [cite: 540][cite_start]Dual Analog Inputs (NTC Thermistors) [cite: 540]
    J3 [cite: 540][cite_start]RS485 Interface [cite: 540]
    J5 [cite: 540][cite_start]Digital Inputs [cite: 540]
    J2, J4 [cite: 540][cite_start]Relay Outputs (Valves and Fan) [cite: 540]