RS232 Shield

From DFRobot Electronic Product Wiki and Tutorial: Arduino and Robot


  • This RS232 shield is designed for the Arduino controller,and it can easily convert UART to RS232 interface.
  • This shield integrates DB9 connectors (female), so it can be easily connected to various RS232 interface devices.Also the shield integrates RS232 headers to facilitate your connection and commissioning.
  • The shield provides the welding areas to maka full use of space on it. And it's convenient for your DIY design.
  • The shield provides a run / program mode switch. To OFF at the time, to Arduino master programmer;To ON at the time, the shield normal use.
  • Gold immersion PCB. Long pins on the back adapt to most Arduino controllers.


  • Power module: +5V
  • Module size: 55mmx53mm
  • 16 digital IO port (including a I2C interface)
  • 6 analog IO port and power
  • Operation/programming mode switch
  • Transceiver indicating LED
  • DB9 connectors (female), RS232 pins
  • Weldable area
  • Reset button


  • RS232 communication


RS232 Shield (SKU:DFR0259)

pin 2 TXD
pin 3 RXD
pin 5 GND

Operation/programming mode switch
OFF download the program for the Arduino controller
ON convert the UART to the RS232


Connection Diagram

When you install the RS232 shield on your Arduino board, and connect the USB-RS232 converter(DB9 male) with the RS232 shield(DB9 female).Then download the following sample code (Note: Downloading code,operation/programming mode switch must hit the OFF position, otherwise it will lead to the download fails. When downloaded,it is complete to ON, and the shield to normal use).


Sample Code

# This sample codes is for testing the RS232 shiled.
# Editor : YouYou
# Date   : 2013.9.25
# Ver    : 0.1
# Product: RS232 shield
# SKU    : DFR0258
int led = 13;
void setup()
void loop()
  int temp;


Open serial monitor of Arduino IDE, find USB-RS232 converter corresponding serial port, send character "V", you can see the LED status may change, and reply "OK".

Trouble shooting

More question and cool idea, visit DFRobot Forum


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