{"product_id":"ch9121-serial-to-ethernet-network-module-ttl-tcpip-3-3v-5v","title":"CH9121 Serial to Ethernet Module TTL TCP\/IP 3.3V 5V STM32","description":"\n\u003ch2\u003eCH9121 Serial Port to Ethernet Network Module — Industrial-Grade TTL Connectivity\u003c\/h2\u003e\n\u003cp\u003eBridge the gap between serial devices and Ethernet networks with the \u003cstrong\u003eCH9121 Serial to Ethernet Network Module\u003c\/strong\u003e. Designed for industrial microcontroller applications, this compact module supports \u003cstrong\u003eSTM32, 51-series MCUs\u003c\/strong\u003e, and virtually any TTL-level serial device. With dual voltage support (3.3V and 5V), plug-and-play TCP\/IP stack, and robust 2KV electromagnetic isolation, it's the go-to solution for engineers and makers who need reliable, high-speed serial-to-network conversion.\u003c\/p\u003e\n\n\u003cp\u003eMade in Mainland China.\u003c\/p\u003e\n\n\u003ch3\u003eKey Features\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eTCP\/IP Protocol Stack:\u003c\/strong\u003e Supports IP, ARP, TCP, UDP, ICMP, IGMP, DHCP — no external stack library needed\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eDual Voltage Support:\u003c\/strong\u003e Works at 3.3V or 5V DC for maximum compatibility with your existing hardware\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFast Ethernet:\u003c\/strong\u003e 10\/100 Mbps RJ45 interface with 6K byte data cache\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFlexible Baud Rate:\u003c\/strong\u003e 300 to 921,600 bps — covers the full range of serial communication speeds\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e2KV Electromagnetic Isolation:\u003c\/strong\u003e Industrial-grade protection for noisy environments\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eEasy Configuration:\u003c\/strong\u003e Set up via network configuration software or serial AT commands\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eRS485 Ready:\u003c\/strong\u003e DIR pin for RS485 send\/receive switching control\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  \u003cthead\u003e\n    \u003ctr style=\"background:#f2f2f2;\"\u003e\n      \u003cth style=\"border:1px solid #ccc; padding:8px; text-align:left;\"\u003eParameter\u003c\/th\u003e\n      \u003cth style=\"border:1px solid #ccc; padding:8px; text-align:left;\"\u003eSpecification\u003c\/th\u003e\n    \u003c\/tr\u003e\n  \u003c\/thead\u003e\n  \u003ctbody\u003e\n    \u003ctr\u003e\n\u003ctd style=\"border:1px solid #ccc; padding:8px;\"\u003eEthernet Interface\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #ccc; padding:8px;\"\u003eRJ45, 10\/100 Mbps\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd style=\"border:1px solid #ccc; padding:8px;\"\u003eEthernet Data Cache\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #ccc; padding:8px;\"\u003e6K bytes\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd style=\"border:1px solid #ccc; padding:8px;\"\u003eNetwork Protocols\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #ccc; padding:8px;\"\u003eIP, ARP, TCP, UDP, ICMP, IGMP, DHCP\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd style=\"border:1px solid #ccc; padding:8px;\"\u003eSerial Interface\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #ccc; padding:8px;\"\u003eTTL, 2.54mm pin header\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd style=\"border:1px solid #ccc; padding:8px;\"\u003eVoltage\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #ccc; padding:8px;\"\u003e3.3V or 5V DC\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd style=\"border:1px solid #ccc; padding:8px;\"\u003eOperating Current\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #ccc; padding:8px;\"\u003e200mA @ 5V\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd style=\"border:1px solid #ccc; padding:8px;\"\u003eBaud Rate\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #ccc; padding:8px;\"\u003e300 – 921,600 bps\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd style=\"border:1px solid #ccc; padding:8px;\"\u003eData Bits\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #ccc; padding:8px;\"\u003e5, 6, 7, 8, 9\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd style=\"border:1px solid #ccc; padding:8px;\"\u003eStop Bits\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #ccc; padding:8px;\"\u003e1, 2\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd style=\"border:1px solid #ccc; padding:8px;\"\u003eParity\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #ccc; padding:8px;\"\u003eNone \/ Odd \/ Even\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd style=\"border:1px solid #ccc; padding:8px;\"\u003eSerial Cache\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #ccc; padding:8px;\"\u003e2K bytes\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd style=\"border:1px solid #ccc; padding:8px;\"\u003eElectromagnetic Isolation\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #ccc; padding:8px;\"\u003e2KV\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd style=\"border:1px solid #ccc; padding:8px;\"\u003eMaterial\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #ccc; padding:8px;\"\u003ePlastic + Metal\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd style=\"border:1px solid #ccc; padding:8px;\"\u003eColor\u003c\/td\u003e\n\u003ctd style=\"border:1px solid #ccc; padding:8px;\"\u003eBlue + Silver\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003ch3\u003ePin Description\u003c\/h3\u003e\n\u003col\u003e\n  \u003cli\u003e\n\u003cstrong\u003eRESET\u003c\/strong\u003e — Factory reset pin; active low, detected at power-on\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eDIR\u003c\/strong\u003e — RS485 receive\/send switch control pin\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eTCPCS\u003c\/strong\u003e — TCP client mode connection status indicator; outputs low on successful connection\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eRUN\u003c\/strong\u003e — Module running status indicator; outputs 2Hz square wave\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eGND\u003c\/strong\u003e — Power ground\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e3.3V\u003c\/strong\u003e — 3.3V DC power input (\u0026gt;200mA); alternative to 5V supply\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eGND\u003c\/strong\u003e — Power ground\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e5V\u003c\/strong\u003e — 5V DC power input (\u0026gt;200mA); alternative to 3.3V supply\u003c\/li\u003e\n\u003c\/ol\u003e\n\n\u003ch3\u003eWhat's in the Box\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e1 × CH9121 Serial Port to Ethernet Network Module\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003e\u003cem\u003eNote: Due to lighting and display variations, the actual color may differ slightly from product images. Measurement tolerance: ±1–3 cm.\u003c\/em\u003e\u003c\/p\u003e\n\n\u003ch3\u003eLearn More About Industrial Networking Standards\u003c\/h3\u003e\n\u003cp\u003eFor background on industrial communication protocols and network standards, visit the \u003ca href=\"https:\/\/www.nist.gov\/topics\/networking\" target=\"_blank\" rel=\"noopener noreferrer\"\u003eNational Institute of Standards and Technology (NIST) Networking Resources\u003c\/a\u003e.\u003c\/p\u003e\n\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003ch4\u003eQ: Is the CH9121 Ethernet module compatible with both STM32 and 51-series microcontrollers?\u003c\/h4\u003e\n\u003cp\u003eA: Yes. The CH9121 Serial to Ethernet Network Module supports TTL-level serial communication at 3.3V or 5V, making it directly compatible with STM32, 51-series MCUs, Arduino, and most other microcontrollers that use a standard UART\/serial interface.\u003c\/p\u003e\n\n\u003ch4\u003eQ: How do I configure the CH9121 module's network settings?\u003c\/h4\u003e\n\u003cp\u003eA: The CH9121 module can be configured in two ways: using the included network configuration software (run over Ethernet) or by sending AT commands directly over the serial port. This makes it easy to set IP address, port number, baud rate, and operating mode (TCP server, TCP client, UDP, etc.) without additional hardware.\u003c\/p\u003e\n\n\u003ch4\u003eQ: Can this module be used in industrial environments?\u003c\/h4\u003e\n\u003cp\u003eA: Absolutely. The CH9121 module features 2KV electromagnetic isolation on the Ethernet interface, making it well-suited for industrial automation, factory floor equipment, PLCs, and other environments where electrical noise is a concern.\u003c\/p\u003e\n\n\u003ch4\u003eQ: What network protocols does the CH9121 module support?\u003c\/h4\u003e\n\u003cp\u003eA: The module's onboard TCP\/IP stack supports IP, ARP, TCP, UDP, ICMP, IGMP, and DHCP — covering the vast majority of use cases for device-to-network and device-to-cloud connectivity in both commercial and industrial applications.\u003c\/p\u003e\n\n\u003cscript type=\"application\/ld+json\"\u003e{\"@context\": \"https:\/\/schema.org\", \"@type\": \"FAQPage\", \"mainEntity\": [{\"@type\": \"Question\", \"name\": \"Is the CH9121 Ethernet module compatible with both STM32 and 51-series microcontrollers?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"Yes. 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The CH9121 module features 2KV electromagnetic isolation on the Ethernet interface, making it well-suited for industrial automation, factory floor equipment, PLCs, and other environments where electrical noise is a concern.\"}}, {\"@type\": \"Question\", \"name\": \"What network protocols does the CH9121 module support?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"The module's onboard TCP\/IP stack supports IP, ARP, TCP, UDP, ICMP, IGMP, and DHCP — covering the vast majority of use cases for device-to-network and device-to-cloud connectivity in both commercial and industrial applications.\"}}]}\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\": \"CH9121 Serial to Ethernet Module TTL TCP\/IP 3.3V 5V STM32\", \"item\": \"https:\/\/kujrmc-0q.myshopify.com\/products\/ch9121-serial-to-ethernet-network-module-ttl-tcpip-3-3v-5v\"}]}\u003c\/script\u003e","brand":"Vue","offers":[{"title":"BlueSilver","offer_id":48753213046976,"sku":"14:173#BlueSilver","price":47.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0772\/9338\/7968\/files\/Sab52db0b40c54bf18d6d63f17850ab3an.webp?v=1786277030","url":"https:\/\/vueselect.com\/products\/ch9121-serial-to-ethernet-network-module-ttl-tcpip-3-3v-5v","provider":"Vue","version":"1.0","type":"link"}