{"product_id":"7-24v-modbus-rtu-4-channel-rs232-serial-relay-module","title":"7-24V Modbus RTU 4 Channel RS232 Serial Relay Module","description":"\u003cmeta name=\"description\" content=\"Buy 7-24V Modbus RTU 4 Channel RS232 Serial Relay Module online in India at best price from The Engineer Store, Bengaluru. Authentic product, 7-day warranty on manufacturing defects, fast delivery across India.\"\u003e\n\n\u003ch1\u003e7-24V Modbus RTU 4 Channel RS232 Serial Relay Module\u003c\/h1\u003e\n\n\u003cp\u003eThe 7-24V Modbus RTU 4 Channel RS232 Serial Relay Module is an industrial-grade control interface that enables remote switching of high-power loads through serial communication protocols. Industrial automation engineers, SCADA system integrators, and IoT developers use this module to establish reliable communication between host controllers and external relay circuits without requiring direct GPIO connections. This module solves the critical challenge of galvanic isolation and long-distance relay control in distributed automation systems where multiple devices must be managed through a single RS232 serial port.\u003c\/p\u003e\n\n\u003ch2\u003eProduct Overview\u003c\/h2\u003e\n\u003cp\u003eThis relay module operates as a Modbus RTU slave device, converting serial RS232 commands into four independent relay switching outputs. The module features a wide input voltage range of 7-24V DC, making it compatible with various power supply standards used in industrial environments. Each relay channel is optically isolated from the control circuit, preventing ground loop issues and protecting sensitive microcontrollers from voltage spikes and electromagnetic interference. The Modbus RTU protocol implementation allows seamless integration with existing industrial control systems, PLCs, and SCADA software without requiring custom driver development.\u003c\/p\u003e\n\n\u003cp\u003eThe architecture employs a dedicated microcontroller that interprets incoming Modbus frames, validates checksums, and executes relay switching commands with millisecond response times. Each relay output is rated for standard industrial loads, with integrated flywheel diodes protecting against inductive kickback from solenoids and motor coils. The RS232 interface operates at standard baud rates from 1200 to 115200 bps, with configurable slave addresses allowing multiple modules to operate on a single serial bus. This modular design eliminates the need for complex relay wiring and provides a standardized interface for industrial automation projects.\u003c\/p\u003e\n\n\u003ch2\u003eKey Specifications\u003c\/h2\u003e\n\u003ctable\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpecification\u003c\/td\u003e\n\u003ctd\u003eDetails\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eProduct Type\u003c\/td\u003e\n\u003ctd\u003eModbus RTU 4 Channel Serial Relay Control Module\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBrand\u003c\/td\u003e\n\u003ctd\u003eGeneric Industrial Grade\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOrigin\u003c\/td\u003e\n\u003ctd\u003eOriginal\/Authentic\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWarranty\u003c\/td\u003e\n\u003ctd\u003e7 days on manufacturing defects\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eShipping\u003c\/td\u003e\n\u003ctd\u003e1-5 days from Bengaluru\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDelivery\u003c\/td\u003e\n\u003ctd\u003e7-8 days across India\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSupport\u003c\/td\u003e\n\u003ctd\u003e24\/7 via Email and WhatsApp\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eInput Voltage Range\u003c\/td\u003e\n\u003ctd\u003e7-24V DC\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNumber of Relay Channels\u003c\/td\u003e\n\u003ctd\u003e4 Independent Channels\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCommunication Protocol\u003c\/td\u003e\n\u003ctd\u003eModbus RTU Serial Standard\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eInterface Type\u003c\/td\u003e\n\u003ctd\u003eRS232 Serial Port\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBaud Rate\u003c\/td\u003e\n\u003ctd\u003e1200 to 115200 bps (Configurable)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRelay Contact Rating\u003c\/td\u003e\n\u003ctd\u003e10A at 250V AC \/ 30V DC per channel\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptical Isolation\u003c\/td\u003e\n\u003ctd\u003eYes, 2500V isolation between control and relay circuits\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eResponse Time\u003c\/td\u003e\n\u003ctd\u003eLess than 100ms per command\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOperating Temperature\u003c\/td\u003e\n\u003ctd\u003e-20 to +70 degrees Celsius\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDimensions\u003c\/td\u003e\n\u003ctd\u003eCompact DIN rail mountable form factor\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\n\n\u003ch2\u003eKey Features\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003eWide Input Voltage Range: 7-24V DC operation ensures compatibility with 12V, 18V, and 24V industrial power supplies without additional regulators\u003c\/li\u003e\n\u003cli\u003eModbus RTU Protocol Support: Industry-standard serial communication enables plug-and-play integration with PLC systems, SCADA software, and industrial controllers\u003c\/li\u003e\n\u003cli\u003eOptical Isolation Technology: 2500V isolation between control and relay circuits protects microcontrollers from voltage transients and ground loop faults\u003c\/li\u003e\n\u003cli\u003eFour Independent Relay Channels: Each channel operates independently with 10A contact rating, supporting simultaneous multi-load switching scenarios\u003c\/li\u003e\n\u003cli\u003eConfigurable Slave Addressing: Support for multiple slave addresses allows daisy-chaining up to 247 modules on a single RS232 serial bus\u003c\/li\u003e\n\u003cli\u003eFast Response Time: Sub-100ms switching response ensures real-time control in time-critical automation applications\u003c\/li\u003e\n\u003cli\u003eBuilt-in Protection: Integrated flywheel diodes and surge suppression protect relay contacts from inductive load damage\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eApplications and Use Cases\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003eSCADA Systems: Remote monitoring and control of water pumps, compressors, and industrial motors in distributed automation networks across multiple facility locations\u003c\/li\u003e\n\u003cli\u003eBuilding Automation: Centralized control of HVAC systems, lighting circuits, and access control systems through networked PLC controllers in commercial buildings\u003c\/li\u003e\n\u003cli\u003eManufacturing Process Control: Sequential relay switching for conveyor systems, pneumatic actuators, and solenoid valves in assembly line automation\u003c\/li\u003e\n\u003cli\u003eIoT and Remote Monitoring: Integration with Raspberry Pi, Arduino, and industrial gateways for remote equipment shutdown, alarm triggering, and emergency control scenarios\u003c\/li\u003e\n\u003cli\u003eGreenhouse and Agricultural Automation: Automated control of irrigation pumps, ventilation fans, and grow light circuits based on sensor inputs and scheduled timing\u003c\/li\u003e\n\u003cli\u003eRenewable Energy Systems: Relay switching for solar inverter load management, battery charging circuits, and backup generator activation in off-grid installations\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eHow to Use\u003c\/h2\u003e\n\u003cp\u003eBegin by connecting the 7-24V DC power supply to the module's power input terminals, ensuring correct polarity to prevent component damage. Connect your RS232 serial port from the host controller (PLC, industrial computer, or microcontroller board) to the module's RS232 connector using a standard serial cable. Configure the module's slave address and baud rate using the onboard DIP switches or configuration software to match your host controller settings. Each relay output terminal can be wired directly to the control coil of contactors, solenoids, or directly to low-power loads, with the module providing galvanic isolation from the control circuit.\u003c\/p\u003e\n\n\u003cp\u003eImplement Modbus RTU commands in your host controller software to read relay status and send switching commands using standard function codes 01 (Read Coil Status) and 05 (Write Single Coil). Test communication by sending a simple command to toggle a relay and verify the physical relay activation with an audible click. For multi-module setups, assign unique slave addresses to each module and implement proper error handling for timeouts and CRC failures. Always include protective wiring such as fuses on relay output circuits and use proper cable shielding for RS232 lines in electrically noisy industrial environments to ensure reliable long-distance communication.\u003c\/p\u003e\n\n\u003ch2\u003eFrequently Asked Questions\u003c\/h2\u003e\n\u003cdetails\u003e\n\u003csummary\u003eWhat is the maximum distance for RS232 communication with this module?\u003c\/summary\u003e\n\u003cp\u003eStandard RS232 specifications support reliable communication up to 15 meters without signal conditioning. For longer distances up to 1200 meters, implement RS232 to RS485 converters on both the host and module sides. The Modbus RTU protocol remains fully compatible with RS485 conversion, allowing industrial installations to extend control networks across large facility areas without signal degradation.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eCan I operate multiple relay modules on a single RS232 port?\u003c\/summary\u003e\n\u003cp\u003eYes, this module supports Modbus RTU multi-drop networking, allowing up to 247 modules on a single serial bus. Each module must be assigned a unique slave address using the onboard DIP switches. Your host controller sends commands specifying the target slave address, and only that module responds, enabling centralized control of multiple relay banks from a single serial port without additional hardware.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eWhat relay load types are compatible with this module?\u003c\/summary\u003e\n\u003cp\u003eThe relay contacts are rated for 10A at 250V AC or 30V DC, making them suitable for inductive loads like solenoids and motor coils, resistive loads like heaters and incandescent lights, and capacitive loads with proper suppression. Always use flywheel diodes for inductive loads and varistors for AC loads to protect relay contacts from arcing and premature failure. Avoid switching loads exceeding the rated specifications to ensure long module lifespan.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eHow do I handle communication errors and timeouts?\u003c\/summary\u003e\n\u003cp\u003eImplement timeout detection in your host controller software by monitoring for response frames within 100-200ms of sending a command. If no response is received, the module may be offline or the serial connection is faulty. Verify baud rate matching, slave address configuration, and cable connections. Implement CRC checksum validation on all received frames to detect corrupted data. Most industrial controllers include built-in Modbus error handling functions that automatically retry failed commands and log communication faults.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eWhen will I receive my order?\u003c\/summary\u003e\n\u003cp\u003eOrders are dispatched within 1-5 business days from our Bengaluru warehouse. Delivery takes 7-8 days to most locations across India.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eWhat is your return and warranty policy?\u003c\/summary\u003e\n\u003cp\u003eWe offer a 7-day return policy on manufacturing defects only. Contact support within 7 days of receipt for free replacement or full refund. Not applicable for user damage or misuse.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eAre bulk discounts available?\u003c\/summary\u003e\n\u003cp\u003eYes, wholesale pricing for orders of 10 or more units. Contact our sales team via WhatsApp or email for a customized bulk quote.\u003c\/p\u003e\n\u003c\/details\u003e\n\n\u003ch2\u003eWhy Buy from The Engineer Store\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003eGenuine Products: Sourced directly from authorized distributors with authentication\u003c\/li\u003e\n\u003cli\u003eExpert Team: Our technical team validates every product before listing\u003c\/li\u003e\n\u003cli\u003eFast Shipping: Dispatched within 1-5 days from our Bengaluru warehouse\u003c\/li\u003e\n\u003cli\u003ePan-India Delivery: 7-8 days to Mumbai, Delhi, Chennai, Hyderabad, Pune, Kolkata\u003c\/li\u003e\n\u003cli\u003ePayment Options: COD, UPI, credit\/debit cards, net banking, EMI available\u003c\/li\u003e\n\u003cli\u003eTechnical Support: 24\/7 expert guidance via email and WhatsApp\u003c\/li\u003e\n\u003cli\u003eReturns: 7-day return policy on manufacturing defects only\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eBuy 7-24V Modbus RTU 4 Channel RS232 Serial Relay Module Online in India\u003c\/h2\u003e\n\u003cp\u003ePurchase the \u003cstrong\u003e7-24V Modbus RTU 4 Channel RS232 Serial Relay Module\u003c\/strong\u003e online at \u003ca href=\"https:\/\/theengineerstore.in\"\u003eThe Engineer Store\u003c\/a\u003e, India's trusted source for genuine electronics. We deliver across Bengaluru, Mumbai, Delhi, Chennai, Hyderabad, Pune, Kolkata, Ahmedabad, Jaipur, and Surat. Get the best price on \u003cstrong\u003e7-24V Modbus RTU 4 Channel RS232 Serial Relay Module\u003c\/strong\u003e with fast shipping and expert support.\u003c\/p\u003e\n\u003cp\u003eOur team in Bengaluru is available 24\/7 to support your journey from product selection to project completion.\u003c\/p\u003e","brand":"My Store","offers":[{"title":"Default Title","offer_id":43874187182243,"sku":"TES-EV100444576","price":942.36,"currency_code":"INR","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0628\/4479\/7091\/products\/7-24V-Modbus-RTU-4-Channel-RS232-Serial-Relay-Module-314x252.jpg?v=1704719117","url":"https:\/\/www.theengineerstore.in\/kn\/products\/7-24v-modbus-rtu-4-channel-rs232-serial-relay-module","provider":"The Engineer Store","version":"1.0","type":"link"}