Connecting Arduino Uno with RDM630 RFID module


I’ve been trying to connect my RFID reader to my Arduino Uno with some vexing results.
Following a whole bunch of tutorials, the one that brings me closest to my desired result can be found on the following site:

#include <SoftwareSerial.h>
SoftwareSerial RFID = SoftwareSerial(4,5);
char character;
String our_id;
void setup()  
void loop(){
      character =;
      our_id += character;
  if (our_id.length() > 10) {
      our_id = our_id.substring(1,13);
      our_id = "";

The problem I’m having is that the data I receive in my Serial monitor consists of the character “þ” and an occasional “ÿ”. My full ID’s look like this: “þþþþþþþþþþ”. Also, if I change my data type on character to int, all I get is 254 254 254 254 254 254… etc.

If anyone could enlighten me on why the Arduino sends me the wrong value back I’d be eternally grateful!


Also, worth to mention. I've checked my RFID-cards with another external USB-based reader and they all have their own unique IDs.

Check your wiring. You probably aren't grounding something that should be grounded.

Check your wiring. You probably aren’t grounding something that should be grounded.

Or he has a baud-rate mismatch problem…

Thanks for your replies, although they didn't really bring me closer to a working solution.

As for the wiring. It's super simple so far so nothing should be connected strangely. (Image attached)

I'm not 100% sure how the baud rates work but the specification sheet for the RFID-chip tells me it's supposed to run on 9600 baud: I've tried all rates between 300 and 115200 but had no change in luck. Although, when using some rates I get another character as a result but it's always mumble jumble.