Example Code for Arduino-RS232 Communication Test
Last revision 2025/12/08
This article explains how to conduct a communication test between Arduino microcontrollers and RS232 devices using an RS232 shield and a USB-RS232 converter. It includes detailed hardware and software preparation, wiring diagrams, and a sample code for toggling an LED based on received serial data.
Hardware Preparation
- RS232 Shield for Arduino(SKU:DFR0258) x1
- DFRduino UNO R3(SKU:DFR0216) x1
- USB-RS232 Converter x1
Software Preparation
- Download and install Arduino IDE:[Download Link]
Wiring Diagram
| Step Sequence | Connection Operation |
|---|---|
| 1 | Plug the RS232 Shield into the Arduino microcontroller |
| 2 | Connect the DB9 male connector of the USB-RS232 converter to the DB9 female connector of the RS232 Shield |
Sample Code
# This sample codes is for testing the RS232 shiled.
# Editor : YouYou
# Date : 2013.9.25
# Ver : 0.1
# Product: RS232 shield
# SKU : DFR0259
*/
int led = 13; //define the LED pin
void setup()
{
Serial.begin(9600); //init serial
pinMode(led,OUTPUT);
}
void loop()
{
int temp; //serial data temporary cache
if(Serial.available()) //if serial receives data
{
temp=Serial.read(); //store the received data temporarily
if(temp=='V'){
digitalWrite(led,1-digitalRead(led)); //change the LED statu if receiving the char "V".
Serial.println("OK"); //reply OK to show that the char "V" has been received and the LED statu also has been changed
}
}
}
Result
Open the Serial debugger, find the COM related with USB-RS232, send a char "V", then the LED statu will be changed and it will reply "OK".
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