{"product_id":"esp32-4-channel-relay-module-rs485-modbus-rtu-development-board","title":"ESP32 4-Channel Relay Module RS485 Modbus RTU Board","description":"\n\u003ch2\u003eESP32 4-Channel Relay Module with RS485 \u0026amp; Modbus RTU Support\u003c\/h2\u003e\n\u003cp\u003eTake your automation and IoT projects to the next level with this versatile \u003cstrong\u003eESP32 Four-Channel Relay Module\u003c\/strong\u003e. Featuring built-in Wi-Fi and Bluetooth via the ESP32 microcontroller, RS485 communication, and full Modbus RTU protocol support, this development board is engineered for reliable, scalable control applications — from industrial automation to smart home systems.\u003c\/p\u003e\n\n\u003ch3\u003eKey Features\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eESP32 Microcontroller\u003c\/strong\u003e — Onboard Wi-Fi and Bluetooth connectivity for wireless control and IoT integration\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e4-Channel Relay Output\u003c\/strong\u003e — Control up to four independent circuits simultaneously with high-current relay switching\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFull Optocoupler Isolation\u003c\/strong\u003e — Both input and output sides are optocoupler-isolated, protecting your microcontroller and sensitive circuitry from high-voltage transients\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eRS485 Interface with Modbus RTU Protocol\u003c\/strong\u003e — Industry-standard communication for long-distance, noise-resistant data transmission in professional environments\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eBuilt-in CH340 Serial Port Chip\u003c\/strong\u003e — Seamless USB-to-serial conversion for easy programming and debugging via standard tools\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFlexible Power Input\u003c\/strong\u003e — Accepts 9–24V DC power supply as well as USB Type-C, giving you flexible installation options in the field or on the bench\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCompact Form Factor\u003c\/strong\u003e — Measures just 93mm × 87mm, making it easy to integrate into enclosures and project builds\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eTechnical Specifications\u003c\/h3\u003e\n\u003ctable\u003e\n  \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eMicrocontroller\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eESP32 (Wi-Fi + Bluetooth)\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eRelay Channels\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e4\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eCommunication\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eRS485 \/ Modbus RTU\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eIsolation\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eOptocoupler (Input \u0026amp; Output)\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eSerial Chip\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eCH340\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003ePower Input\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e9–24V DC or USB Type-C\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eBoard Dimensions\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e93mm × 87mm\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eVoltage Classification\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eLow Voltage (Below 50V AC \/ 75V DC)\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eCountry of Origin\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eMade in China\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\n\n\u003ch3\u003eWhat's in the Box\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e1× ESP32 4-Channel Relay Module (RS485 \/ Modbus RTU Development Board)\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eIdeal Applications\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003eIndustrial automation and process control\u003c\/li\u003e\n  \u003cli\u003eSmart home and building automation\u003c\/li\u003e\n  \u003cli\u003eRemote switching and monitoring systems\u003c\/li\u003e\n  \u003cli\u003eDIY electronics and IoT prototyping\u003c\/li\u003e\n  \u003cli\u003ePLC-to-device communication bridges\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003e\u003cstrong\u003eNote:\u003c\/strong\u003e Due to lighting and display variation, colors may appear slightly different from product images. Please allow ±1–10mm dimensional tolerance due to manual measurement.\u003c\/p\u003e\n\n\u003cp\u003eFor guidance on safe handling of electrical and electronic development boards, refer to the U.S. Consumer Product Safety Commission – Electrical Safety Resources.\u003c\/p\u003e\n\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003ch4\u003eQ: Does this ESP32 relay module support wireless programming over Wi-Fi?\u003c\/h4\u003e\n\u003cp\u003eA: Yes! The onboard ESP32 chip includes both Wi-Fi and Bluetooth, enabling over-the-air (OTA) firmware updates and wireless communication with IoT platforms and home automation systems.\u003c\/p\u003e\n\n\u003ch4\u003eQ: What is the purpose of optocoupler isolation on this relay board?\u003c\/h4\u003e\n\u003cp\u003eA: Optocoupler isolation electrically separates the control-side (your microcontroller or computer) from the relay-side (high-voltage loads). This protects sensitive components from voltage spikes and interference, improving reliability and safety in your projects.\u003c\/p\u003e\n\n\u003ch4\u003eQ: Can I use this board with both USB Type-C and DC power simultaneously?\u003c\/h4\u003e\n\u003cp\u003eA: The board supports 9–24V DC input as well as USB Type-C power. It is recommended to use one power source at a time; refer to your specific setup requirements and the board's power input circuitry before connecting both simultaneously.\u003c\/p\u003e\n\n\u003ch4\u003eQ: What software or libraries do I need to program this ESP32 Modbus relay board?\u003c\/h4\u003e\n\u003cp\u003eA: You can program it using the Arduino IDE with ESP32 board support installed, or using the ESP-IDF framework. For Modbus RTU, libraries such as ModbusMaster or ESP32 Modbus are commonly used. The built-in CH340 chip means most systems will recognize the board as a standard COM\/serial port without additional drivers.\u003c\/p\u003e\n\n\u003cscript type=\"application\/ld+json\"\u003e{\"@context\": \"https:\/\/schema.org\", \"@type\": \"FAQPage\", \"mainEntity\": [{\"@type\": \"Question\", \"name\": \"Does this ESP32 relay module support wireless programming over Wi-Fi?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Yes! The onboard ESP32 chip includes both Wi-Fi and Bluetooth, enabling over-the-air (OTA) firmware updates and wireless communication with IoT platforms and home automation systems.\"}}, {\"@type\": \"Question\", \"name\": \"What is the purpose of optocoupler isolation on this relay board?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Optocoupler isolation electrically separates the control-side (your microcontroller or computer) from the relay-side (high-voltage loads). 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