63 % छूट
7-24V Modbus RTU 4 Channel RS232 Serial Relay Module
The 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.
Product Overview
This 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.
The 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.
Key Specifications
| Specification | Details |
| Product Type | Modbus RTU 4 Channel Serial Relay Control Module |
| Brand | Generic Industrial Grade |
| Origin | Original/Authentic |
| Warranty | 7 days on manufacturing defects |
| Shipping | 1-5 days from Bengaluru |
| Delivery | 7-8 days across India |
| Support | 24/7 via Email and WhatsApp |
| Input Voltage Range | 7-24V DC |
| Number of Relay Channels | 4 Independent Channels |
| Communication Protocol | Modbus RTU Serial Standard |
| Interface Type | RS232 Serial Port |
| Baud Rate | 1200 to 115200 bps (Configurable) |
| Relay Contact Rating | 10A at 250V AC / 30V DC per channel |
| Optical Isolation | Yes, 2500V isolation between control and relay circuits |
| Response Time | Less than 100ms per command |
| Operating Temperature | -20 to +70 degrees Celsius |
| Dimensions | Compact DIN rail mountable form factor |
Key Features
- Wide Input Voltage Range: 7-24V DC operation ensures compatibility with 12V, 18V, and 24V industrial power supplies without additional regulators
- Modbus RTU Protocol Support: Industry-standard serial communication enables plug-and-play integration with PLC systems, SCADA software, and industrial controllers
- Optical Isolation Technology: 2500V isolation between control and relay circuits protects microcontrollers from voltage transients and ground loop faults
- Four Independent Relay Channels: Each channel operates independently with 10A contact rating, supporting simultaneous multi-load switching scenarios
- Configurable Slave Addressing: Support for multiple slave addresses allows daisy-chaining up to 247 modules on a single RS232 serial bus
- Fast Response Time: Sub-100ms switching response ensures real-time control in time-critical automation applications
- Built-in Protection: Integrated flywheel diodes and surge suppression protect relay contacts from inductive load damage
Applications and Use Cases
- SCADA Systems: Remote monitoring and control of water pumps, compressors, and industrial motors in distributed automation networks across multiple facility locations
- Building Automation: Centralized control of HVAC systems, lighting circuits, and access control systems through networked PLC controllers in commercial buildings
- Manufacturing Process Control: Sequential relay switching for conveyor systems, pneumatic actuators, and solenoid valves in assembly line automation
- IoT and Remote Monitoring: Integration with Raspberry Pi, Arduino, and industrial gateways for remote equipment shutdown, alarm triggering, and emergency control scenarios
- Greenhouse and Agricultural Automation: Automated control of irrigation pumps, ventilation fans, and grow light circuits based on sensor inputs and scheduled timing
- Renewable Energy Systems: Relay switching for solar inverter load management, battery charging circuits, and backup generator activation in off-grid installations
How to Use
Begin 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.
Implement 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.
Frequently Asked Questions
What is the maximum distance for RS232 communication with this module?
Standard 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.
Can I operate multiple relay modules on a single RS232 port?
Yes, 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.
What relay load types are compatible with this module?
The 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.
How do I handle communication errors and timeouts?
Implement 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.
When will I receive my order?
Orders are dispatched within 1-5 business days from our Bengaluru warehouse. Delivery takes 7-8 days to most locations across India.
What is your return and warranty policy?
We 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.
Are bulk discounts available?
Yes, wholesale pricing for orders of 10 or more units. Contact our sales team via WhatsApp or email for a customized bulk quote.
Why Buy from The Engineer Store
- Genuine Products: Sourced directly from authorized distributors with authentication
- Expert Team: Our technical team validates every product before listing
- Fast Shipping: Dispatched within 1-5 days from our Bengaluru warehouse
- Pan-India Delivery: 7-8 days to Mumbai, Delhi, Chennai, Hyderabad, Pune, Kolkata
- Payment Options: COD, UPI, credit/debit cards, net banking, EMI available
- Technical Support: 24/7 expert guidance via email and WhatsApp
- Returns: 7-day return policy on manufacturing defects only
Buy 7-24V Modbus RTU 4 Channel RS232 Serial Relay Module Online in India
Purchase the 7-24V Modbus RTU 4 Channel RS232 Serial Relay Module online at The Engineer Store, 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 7-24V Modbus RTU 4 Channel RS232 Serial Relay Module with fast shipping and expert support.
Our team in Bengaluru is available 24/7 to support your journey from product selection to project completion.
7-24V Modbus RTU 4 Channel RS232 Serial Relay Module
The 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.
Product Overview
This 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.
The 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.
Key Specifications
| Specification | Details |
| Product Type | Modbus RTU 4 Channel Serial Relay Control Module |
| Brand | Generic Industrial Grade |
| Origin | Original/Authentic |
| Warranty | 7 days on manufacturing defects |
| Shipping | 1-5 days from Bengaluru |
| Delivery | 7-8 days across India |
| Support | 24/7 via Email and WhatsApp |
| Input Voltage Range | 7-24V DC |
| Number of Relay Channels | 4 Independent Channels |
| Communication Protocol | Modbus RTU Serial Standard |
| Interface Type | RS232 Serial Port |
| Baud Rate | 1200 to 115200 bps (Configurable) |
| Relay Contact Rating | 10A at 250V AC / 30V DC per channel |
| Optical Isolation | Yes, 2500V isolation between control and relay circuits |
| Response Time | Less than 100ms per command |
| Operating Temperature | -20 to +70 degrees Celsius |
| Dimensions | Compact DIN rail mountable form factor |
Key Features
- Wide Input Voltage Range: 7-24V DC operation ensures compatibility with 12V, 18V, and 24V industrial power supplies without additional regulators
- Modbus RTU Protocol Support: Industry-standard serial communication enables plug-and-play integration with PLC systems, SCADA software, and industrial controllers
- Optical Isolation Technology: 2500V isolation between control and relay circuits protects microcontrollers from voltage transients and ground loop faults
- Four Independent Relay Channels: Each channel operates independently with 10A contact rating, supporting simultaneous multi-load switching scenarios
- Configurable Slave Addressing: Support for multiple slave addresses allows daisy-chaining up to 247 modules on a single RS232 serial bus
- Fast Response Time: Sub-100ms switching response ensures real-time control in time-critical automation applications
- Built-in Protection: Integrated flywheel diodes and surge suppression protect relay contacts from inductive load damage
Applications and Use Cases
- SCADA Systems: Remote monitoring and control of water pumps, compressors, and industrial motors in distributed automation networks across multiple facility locations
- Building Automation: Centralized control of HVAC systems, lighting circuits, and access control systems through networked PLC controllers in commercial buildings
- Manufacturing Process Control: Sequential relay switching for conveyor systems, pneumatic actuators, and solenoid valves in assembly line automation
- IoT and Remote Monitoring: Integration with Raspberry Pi, Arduino, and industrial gateways for remote equipment shutdown, alarm triggering, and emergency control scenarios
- Greenhouse and Agricultural Automation: Automated control of irrigation pumps, ventilation fans, and grow light circuits based on sensor inputs and scheduled timing
- Renewable Energy Systems: Relay switching for solar inverter load management, battery charging circuits, and backup generator activation in off-grid installations
How to Use
Begin 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.
Implement 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.
Frequently Asked Questions
What is the maximum distance for RS232 communication with this module?
Standard 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.
Can I operate multiple relay modules on a single RS232 port?
Yes, 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.
What relay load types are compatible with this module?
The 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.
How do I handle communication errors and timeouts?
Implement 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.
When will I receive my order?
Orders are dispatched within 1-5 business days from our Bengaluru warehouse. Delivery takes 7-8 days to most locations across India.
What is your return and warranty policy?
We 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.
Are bulk discounts available?
Yes, wholesale pricing for orders of 10 or more units. Contact our sales team via WhatsApp or email for a customized bulk quote.
Why Buy from The Engineer Store
- Genuine Products: Sourced directly from authorized distributors with authentication
- Expert Team: Our technical team validates every product before listing
- Fast Shipping: Dispatched within 1-5 days from our Bengaluru warehouse
- Pan-India Delivery: 7-8 days to Mumbai, Delhi, Chennai, Hyderabad, Pune, Kolkata
- Payment Options: COD, UPI, credit/debit cards, net banking, EMI available
- Technical Support: 24/7 expert guidance via email and WhatsApp
- Returns: 7-day return policy on manufacturing defects only
Buy 7-24V Modbus RTU 4 Channel RS232 Serial Relay Module Online in India
Purchase the 7-24V Modbus RTU 4 Channel RS232 Serial Relay Module online at The Engineer Store, 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 7-24V Modbus RTU 4 Channel RS232 Serial Relay Module with fast shipping and expert support.
Our team in Bengaluru is available 24/7 to support your journey from product selection to project completion.