[SOLVED] RS232 Interface w/ Barcode Scanner


I'm trying to get the data from a Datalogic Gryphon L 4330 Barcode Scanner using a RS232 connection cable on an Arduino UNO. The Signal from the Scanner comes in CMOS Level, so I used a DFrobot RS232 Shield which is basically just a Max232 soldered on a Arduino-shaped Shield PCB.
The Barcode Scanner works with virtually any cheap RS232->USB Converter connected to a PC.
However, the Arduino Serial Monitor doesn't show any input at all.
As the Barcode Scanner has a seperate power supply I assume power is not an issue here.
I am aware that there are several implementations of the RS232 protocol and that the Max232 might or might not be able to translate the input into something useful, however, I'm quite confused that none of the UART-LEDs on the Arduino nor any of the LEDs on the RS232 Shield even flicker and as the datasheet implies, these LEDs on the Shield are basically just tied to the Serial lines so this absolutely makes no sense to me.

Any ideas are greatly appreciated!

You need to post your code so we can see what you can see.
And please use the code button </>so your code looks like thisand is easy to copy to a text editor

Post a link to the datasheet for the shield you are using.

What I/O pins does your shield use for receiving the RS232 data?

Have a look at the examples in Serial Input Basics - simple reliable ways to receive data. There is also a parse example.



Thanks for your reply!

Concerning the code I'm just using the example-Sketch for now:

int incomingByte = 0;

void setup() {

void loop() {

        if (Serial.available() > 0) {

                incomingByte = Serial.read();

                Serial.println(incomingByte, DEC);

This is the Shield I'm using.

And here is its datasheet (schematic).

It seems to be connecting to Pins 0 and 1 on the Uno and that is very inconvenient because they are used for communicating with the PC over the USB cable. The mind boggles at how someone could design that shortcoming into the product. I would ask for my money back on the basis that it is not fit for purpose.

If you have a USB-TTL cable (aka an FTDI cable) you could use Software Serial to create a second serial port and use that to communicate with the PC.

My advice would be to ditch that shield and get another RS232 converter that can connect to two SoftwareSerial pins and leave Pins 0 and 1 free for sending debugging messages to the PC.


I have a RS232 barcode scanner, and a Sparkfun RS232 module. I needed to use a NULL-modem adapter.

Hope this helps.


That worked!! Didn't think of that at all!
Thanks so much, this made my day!

hi, could you configure the datalogic and read the data with arduino? I have the same problem with a datalogic om-3010