How to Use MKE-M20 RS485-TTL GDT: Examples, Pinouts, and Specs

The MKE-M20 RS485-TTL GDT is a versatile module designed to bridge communication between RS485 and TTL logic levels. Manufactured by MakerEdu.vn, this module is ideal for applications requiring robust and reliable data transmission over long distances. It features built-in protection against voltage spikes, ensuring durability and stability in industrial environments.

• Industrial automation and control systems
• Data acquisition systems
• Long-distance serial communication
• Home automation networks
• RS485-based sensor interfacing

1. Power the Module: Connect the VCC pin to a 3.3V or 5V power source and the GND pin to the ground.
2. Connect RS485 Lines: Attach the RS485 differential lines (A and B) to the corresponding RS485 network.
3. Connect TTL Lines: Link the TXD and RXD pins to the microcontroller or TTL-compatible device.
4. Configure Communication: Set the baud rate and communication parameters on your microcontroller to match the RS485 device.

• Ensure proper termination resistors are used on the RS485 bus to prevent signal reflections.
• Avoid connecting the module to power sources exceeding 5V to prevent damage.
• Use twisted-pair cables for RS485 lines to minimize electromagnetic interference (EMI).
• The module is designed for half-duplex communication; ensure proper software handling for data direction.

Below is an example of how to use the MKE-M20 RS485-TTL GDT with an Arduino UNO for communication with an RS485 device.

• VCC → 5V on Arduino
• GND → GND on Arduino
• TXD → Pin 3 on Arduino
• RXD → Pin 2 on Arduino
• A and B → RS485 differential lines

#include <SoftwareSerial.h>

// Define RX and TX pins for SoftwareSerial
#define RX_PIN 2  // Arduino pin connected to RXD on the module
#define TX_PIN 3  // Arduino pin connected to TXD on the module

// Initialize SoftwareSerial for RS485 communication
SoftwareSerial RS485Serial(RX_PIN, TX_PIN);

void setup() {
  // Start serial communication with the RS485 module
  RS485Serial.begin(9600);  // Set baud rate to 9600
  Serial.begin(9600);       // Start Serial Monitor for debugging

  Serial.println("RS485-TTL Communication Initialized");
}

void loop() {
  // Send data to RS485 device
  RS485Serial.println("Hello RS485 Device!");
  Serial.println("Data sent to RS485 device");

  // Wait for a response
  if (RS485Serial.available()) {
    String response = RS485Serial.readString();
    Serial.print("Received: ");
    Serial.println(response);
  }

  delay(1000);  // Wait 1 second before sending the next message
}

1. Can the module operate at 3.3V?

   • Yes, the module supports both 3.3V and 5V logic levels.

2. Is the module compatible with full-duplex RS485 communication?

   • No, the module is designed for half-duplex communication only.

3. What is the maximum cable length supported?

   • The RS485 standard supports cable lengths up to 1200 meters, but actual performance depends on baud rate and cable quality.

4. Does the module require external pull-up or pull-down resistors?

   • No, the module has built-in resistors for proper RS485 line biasing.

By following this documentation, users can effectively integrate the MKE-M20 RS485-TTL GDT into their projects for reliable and robust communication.