Industrial Grade Isolation TTL to RS485 Transparent Transmission Module XY-S485

Product Overview

Core Product Advantages

1. 16KV Full Isolation Design, Strong Anti-Interference
   Built-in high-performance isolated RS485 core chip, independent isolation power and signal isolation circuit, effectively isolate ground loop interference, up to 16KV isolation voltage, greatly improve system stability in complex industrial electromagnetic environment.
2. 3.3V/5V Dual Signal Level Compatible, Wide Voltage Input
   DC 3.0V~5.5V wide power supply range, perfectly match STM32, Arduino, 51 MCU and other 3.3V/5V control boards, no extra level conversion circuit required.
3. Automatic Flow Direction Control, Transparent Transmission
   Integrated automatic sending/receiving direction control chip, no need to control DE/RE pins by MCU program, truly transparent data transmission, greatly simplify programming difficulty.
4. Full Industrial Lightning & Surge Protection
   Equipped with gas discharge tube, thermal reset fuse, bidirectional TVS transient suppression diode multi-stage protection circuit, effectively resist lightning surge, static electricity, power grid surge interference; reserved grounding terminal for outdoor long-distance wiring to enhance lightning protection performance.
5. Built-in 120Ω Terminal Resistor, Multi-node Bus Support
   Onboard 120Ω matching resistor, short the solder pad to enable it for long-distance transmission; single bus supports up to 256 slave nodes, hot-swappable without signal crash.
6. Dual Indicator Lights & Standard Wiring Interface
   TX sending indicator + RX receiving indicator, real-time feedback communication status; TTL side 2.54mm pin header with matching 4P wire, RS485 side lift-type terminal block, easy wiring and installation.

Complete Technical Specifications

Pin Definition

TTL Side (Connect MCU)

1. VCC: Module power input (3.3V/5V)
2. TXD: Module transmit pin, connect MCU RXD
3. RXD: Module receive pin, connect MCU TXD
4. GND: Common ground of module and MCU

RS485 Bus Side

1. A+: RS485 positive signal line
2. B-: RS485 negative signal line
3. Earth: Ground terminal, connect to ground wire for outdoor anti-lightning use

Wiring & Operation Guide

1. MCU Wiring: Connect VCC/TXD/RXD/GND to the corresponding IO of single-chip microcomputer, share GND signal.
2. Bus Wiring: Connect all device A+ together, all B- together; long-distance transmission short the 120Ω resistor pad on the board.
3. Grounding Suggestion: For outdoor long-distance wiring, connect the Earth terminal to protective ground to enhance lightning surge resistance; indoor short-distance use can be left unconnected.
4. Communication Test: Power on the module, send serial data, TX light flashes when sending, RX light flashes when receiving, indicating normal communication.

Application Scenarios

• Industrial field sensor long-distance data collection (temperature/humidity, pressure, flow sensor)
• PLC, touch screen, frequency converter RS485 bus communication networking
• Outdoor agricultural greenhouse, breeding environmental monitoring system
• Intelligent building, security equipment centralized monitoring
• Student electronic experiment, embedded serial communication learning project

Important Notes

1. RS485 is half-duplex communication, cannot send and receive data at the same time, data transmission needs time division scheduling.
2. When multiple modules are connected on the same bus, only the two modules at the far left and far right ends need to turn on the 120Ω terminal resistor.
3. Do not reverse VCC and GND power pins, reverse connection will burn the isolation chip and protection circuit.
4. The module supports hot plugging, but avoid plugging and unplugging the bus cable during high-speed data transmission.
5. Slight differences in PCB silkscreen, component color and batch accessories will not affect communication and isolation performance.