SR-201 Series IoT Module: 1. Industrial-grade STC MCU with ENC28J60 and stable firmware supports 6 network connections in TCP server mode, provides UDP control mode, and enables cloud remote control functionality. 2. Control commands are simple: send "11" to turn on the first relay, "21" to turn off the first relay, "11*" for pulse operation of the first relay, "11K" to simulate the first local key (only for models with local key), "11:10" to turn on the first relay for 10 seconds then automatically turn off (delay supports 1–65535 seconds); send "00" to return the status of all channels. 3. Fully supports secondary development. Includes support for local connection and cloud remote control. Demo programs and source code available for PC and mobile devices. Provides module configuration software, timing program, and DLL package for easy integration of configuration functions. 4. Hardware is expandable. Pin layout on the module allows connection to real-time clock, RS-485, Bluetooth, and 2.4GHz modules. 5. 8-bit simplified instruction system offers strong functionality, low development cost, and advantages for customized functions. Module Features: Industrial-grade STC microcontroller as main control chip. Onboard 2-channel high-quality relay with flyback diode circuit. 1 power indicator; each relay has a status indicator (light on indicates relay is closed). Relay module can be expanded up to 8 outputs; note: relay module is active high. Module parameters can be configured via network, such as IP address, gateway, etc. Retains relay state before power-off (configurable). Remote internet control with local password protection for secure and reliable operation. Supports 5–24V DC input voltage; choose one of two power terminals. 1.6mm thick PCB made of industrial-grade FR-4 material; PCB size: 70mm x 50mm with mounting holes. Specifications: Supply voltage: DC 5–24V. Power supply options: 3 x AA batteries, USB port, mobile phone charger, or portable power bank. PCB dimensions: 70mm (L) x 50mm (W). Weight: 51 grams. Interface: +5V: +5V power supply positive, input or output. GND: Power ground, input or output. P30–P35: CH3–CH8 control lines, active high. CLR: Shorten CLR to ground during power-on to restore factory settings. Blue terminal: Connect to user load. Compatible with 220V AC equipment or DC equipment under 30V. Load current must not exceed relay rated capacity. Each relay has one normally open, one normally closed, and one common terminal. When relay is activated, common and normally open contacts connect; when deactivated, common and normally closed contacts connect. Functions: Enables Ethernet and internet-based control of 2-channel relay operation. Relay module can be expanded to 8-channel output via external pin connections. Supports TCP, UDP, and cloud remote control. Commands are simple and intuitive. Delay time from 1 to 65535 seconds can be set directly in the command.