{"product_id":"modbus-rtu-4-channel-relay-module-ac220v-rs485-ttl-uart","title":"Modbus RTU 4-Channel Relay Module AC220V RS485 TTL UART","description":"\n\u003ch2\u003eModbus RTU 4-Channel Relay Module — AC220V Power Supply with RS485\/TTL UART Interface\u003c\/h2\u003e\n\u003cp\u003eTake full control of your automation projects with this robust \u003cstrong\u003e4-Channel Relay Module\u003c\/strong\u003e. Powered directly from AC220V, it features a stable 8-bit MCU, MAX485 level conversion chip, and supports the widely-used \u003cstrong\u003eModbus RTU protocol\u003c\/strong\u003e over RS485 or TTL UART interfaces. Whether you're building an industrial control panel, a smart home automation system, or a prototyping project, this relay board delivers reliable, repeatable performance with power-failure memory preservation built right in.\u003c\/p\u003e\n\n\u003ch3\u003eKey Features\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eAC220V Power Supply:\u003c\/strong\u003e Runs directly from mains voltage — no additional power converter needed.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e4 On-Board Relays:\u003c\/strong\u003e Each relay rated at 10A\/250V AC and 10A\/30V DC, capable of 100,000+ continuous switching cycles.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eModbus RTU Protocol:\u003c\/strong\u003e Industry-standard communication for seamless integration with PLCs, HMIs, and microcontrollers.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eDual Interface Support:\u003c\/strong\u003e Compatible with both RS485 and TTL UART for maximum flexibility.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eAdjustable Baud Rate:\u003c\/strong\u003e Supports 4800, 9600, and 19200 bps (default: 9600 bps) — settings preserved through power cycles.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003ePower-Failure Memory Preservation:\u003c\/strong\u003e Device address and baud rate settings are retained even after power loss.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eMultiple Output Modes:\u003c\/strong\u003e Supports manual, flash-closing, and flash-breaking modes. Flash delay base is 0.1s with a maximum configurable time of 6553.5s (0xFFFF × 0.1s).\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eOptocoupler Input:\u003c\/strong\u003e Accepts DC 3.3–24V input signals for isolated triggering.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eVisual Indicators:\u003c\/strong\u003e On-board LED indicator lights for each relay channel for quick status monitoring.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eDiode Flyback Protection:\u003c\/strong\u003e Built-in diode protection safeguards against voltage spikes, ensuring long-term circuit reliability.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eConfigurable Device Address:\u003c\/strong\u003e Address range 1–255 (default: 255), power-off preserved.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eTechnical Specifications\u003c\/h3\u003e\n\u003ctable style=\"width:100%; border-collapse:collapse;\"\u003e\n  \u003ctr style=\"background:#f5f5f5;\"\u003e\n\u003cth style=\"padding:8px; border:1px solid #ddd; text-align:left;\"\u003eParameter\u003c\/th\u003e\n\u003cth style=\"padding:8px; border:1px solid #ddd; text-align:left;\"\u003eValue\u003c\/th\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003ctd style=\"padding:8px; border:1px solid #ddd;\"\u003ePower Supply Voltage\u003c\/td\u003e\n\u003ctd style=\"padding:8px; border:1px solid #ddd;\"\u003eAC 220V\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr style=\"background:#f5f5f5;\"\u003e\n\u003ctd style=\"padding:8px; border:1px solid #ddd;\"\u003eNumber of Relay Channels\u003c\/td\u003e\n\u003ctd style=\"padding:8px; border:1px solid #ddd;\"\u003e4\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003ctd style=\"padding:8px; border:1px solid #ddd;\"\u003eRelay Rating\u003c\/td\u003e\n\u003ctd style=\"padding:8px; border:1px solid #ddd;\"\u003e10A \/ 250V AC  |  10A \/ 30V DC\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr style=\"background:#f5f5f5;\"\u003e\n\u003ctd style=\"padding:8px; border:1px solid #ddd;\"\u003eCommunication Protocol\u003c\/td\u003e\n\u003ctd style=\"padding:8px; border:1px solid #ddd;\"\u003eStandard Modbus RTU\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003ctd style=\"padding:8px; border:1px solid #ddd;\"\u003eCommunication Interface\u003c\/td\u003e\n\u003ctd style=\"padding:8px; border:1px solid #ddd;\"\u003eRS485 \/ TTL UART\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr style=\"background:#f5f5f5;\"\u003e\n\u003ctd style=\"padding:8px; border:1px solid #ddd;\"\u003eBaud Rate\u003c\/td\u003e\n\u003ctd style=\"padding:8px; border:1px solid #ddd;\"\u003e4800 \/ 9600 \/ 19200 bps (default 9600)\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003ctd style=\"padding:8px; border:1px solid #ddd;\"\u003eOptocoupler Input Range\u003c\/td\u003e\n\u003ctd style=\"padding:8px; border:1px solid #ddd;\"\u003eDC 3.3V – 24V\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr style=\"background:#f5f5f5;\"\u003e\n\u003ctd style=\"padding:8px; border:1px solid #ddd;\"\u003eDevice Address Range\u003c\/td\u003e\n\u003ctd style=\"padding:8px; border:1px solid #ddd;\"\u003e1 – 255 (default 255)\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003ctd style=\"padding:8px; border:1px solid #ddd;\"\u003eRelay Lifespan\u003c\/td\u003e\n\u003ctd style=\"padding:8px; border:1px solid #ddd;\"\u003e100,000+ cycles\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr style=\"background:#f5f5f5;\"\u003e\n\u003ctd style=\"padding:8px; border:1px solid #ddd;\"\u003eCountry of Origin\u003c\/td\u003e\n\u003ctd style=\"padding:8px; border:1px solid #ddd;\"\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× 4-Channel Relay Module Board\u003c\/li\u003e\n  \u003cli\u003e\n\u003cem\u003eOr\u003c\/em\u003e 1× Protective Shell (depending on variant selected)\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eSafety \u0026amp; Compliance\u003c\/h3\u003e\n\u003cp\u003eWhen working with mains-voltage (AC220V) equipment, always follow proper electrical safety practices. For guidance on safe electrical wiring and handling, refer to \u003ca href=\"https:\/\/www.osha.gov\/electrical\" target=\"_blank\" rel=\"noopener noreferrer\"\u003eOSHA Electrical Safety Standards\u003c\/a\u003e.\u003c\/p\u003e\n\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003ch4\u003eQ: What communication protocols does this 4-channel relay module support?\u003c\/h4\u003e\n\u003cp\u003eA: This relay board supports the standard \u003cstrong\u003eModbus RTU protocol\u003c\/strong\u003e and is compatible with both \u003cstrong\u003eRS485\u003c\/strong\u003e and \u003cstrong\u003eTTL UART\u003c\/strong\u003e interfaces, making it easy to integrate with a wide range of PLCs, microcontrollers (such as Arduino or Raspberry Pi), and industrial HMI systems.\u003c\/p\u003e\n\n\u003ch4\u003eQ: Will the relay module retain its settings after a power outage?\u003c\/h4\u003e\n\u003cp\u003eA: Yes. This module features \u003cstrong\u003epower-failure preservation\u003c\/strong\u003e, meaning the configured baud rate and device address are stored in non-volatile memory and will be retained even after the power is completely cut. No reconfiguration is needed upon restart.\u003c\/p\u003e\n\n\u003ch4\u003eQ: What is the maximum load each relay channel can switch?\u003c\/h4\u003e\n\u003cp\u003eA: Each of the four on-board relays is rated at \u003cstrong\u003e10A \/ 250V AC\u003c\/strong\u003e for AC loads and \u003cstrong\u003e10A \/ 30V DC\u003c\/strong\u003e for DC loads, making them suitable for controlling lighting, motors, solenoid valves, and other moderate-power devices.\u003c\/p\u003e\n\n\u003ch4\u003eQ: Can I use the optocoupler input to control the relays directly?\u003c\/h4\u003e\n\u003cp\u003eA: No — the optocoupler input (DC 3.3–24V) is intended for isolated signal input and \u003cstrong\u003ecannot be used directly for relay control\u003c\/strong\u003e. Relay switching is managed via the Modbus RTU commands sent over the RS485 or TTL UART interface.\u003c\/p\u003e\n\n\u003cscript type=\"application\/ld+json\"\u003e{\"@context\": \"https:\/\/schema.org\", \"@type\": \"FAQPage\", \"mainEntity\": [{\"@type\": \"Question\", \"name\": \"What communication protocols does this 4-channel relay module support?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"This relay board supports the standard Modbus RTU protocol and is compatible with both RS485 and TTL UART interfaces, making it easy to integrate with a wide range of PLCs, microcontrollers (such as Arduino or Raspberry Pi), and industrial HMI systems.\"}}, {\"@type\": \"Question\", \"name\": \"Will the relay module retain its settings after a power outage?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Yes. This module features power-failure preservation, meaning the configured baud rate and device address are stored in non-volatile memory and will be retained even after the power is completely cut. No reconfiguration is needed upon restart.\"}}, {\"@type\": \"Question\", \"name\": \"What is the maximum load each relay channel can switch?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Each of the four on-board relays is rated at 10A \/ 250V AC for AC loads and 10A \/ 30V DC for DC loads, making them suitable for controlling lighting, motors, solenoid valves, and other moderate-power devices.\"}}, {\"@type\": \"Question\", \"name\": \"Can I use the optocoupler input to control the relays directly?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"No — the optocoupler input (DC 3.3–24V) is intended for isolated signal input and cannot be used directly for relay control. Relay switching is managed via the Modbus RTU commands sent over the RS485 or TTL UART interface.\"}}]}\u003c\/script\u003e\n\u003cscript type=\"application\/ld+json\"\u003e{\"@context\": \"https:\/\/schema.org\", \"@type\": \"BreadcrumbList\", \"itemListElement\": [{\"@type\": \"ListItem\", \"position\": 1, \"name\": \"Home\", \"item\": \"https:\/\/kujrmc-0q.myshopify.com\/\"}, {\"@type\": \"ListItem\", \"position\": 2, \"name\": \"Electronics \u0026 Tech\", \"item\": \"https:\/\/kujrmc-0q.myshopify.com\/collections\/electronics-tech\"}, {\"@type\": \"ListItem\", \"position\": 3, \"name\": \"Modbus RTU 4-Channel Relay Module AC220V RS485 TTL UART\", \"item\": \"https:\/\/kujrmc-0q.myshopify.com\/products\/modbus-rtu-4-channel-relay-module-ac220v-rs485-ttl-uart\"}]}\u003c\/script\u003e","brand":"Vue","offers":[{"title":"Only Shell","offer_id":48749836665024,"sku":"5:200004763#Only Shell","price":24.99,"currency_code":"USD","in_stock":true},{"title":"Only Relay","offer_id":48749836697792,"sku":"5:144170022#Only Relay","price":24.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0772\/9338\/7968\/files\/Sc2dc76e49e8e43d1a1000cce58d27797w.webp?v=1786209350","url":"https:\/\/vueselect.com\/products\/modbus-rtu-4-channel-relay-module-ac220v-rs485-ttl-uart","provider":"Vue","version":"1.0","type":"link"}