RDM630 RFID reader Problems

Hi there,

I'm currently doing some tests with Arduino and an RDM630 RFID-reader, but the RFID reader is behaving a little strange.

The circuit is fairly simple and the sketch simple as well. The output of the RFID reader is connected to arduino pin #4 which is being read by a SoftwareSerial object. When a code is read it is being compared against one known code.

However, it seems that in my construction the arduino is not receiving rfid codes in a consistent way. Sometimes the RFID reader sends the codes fluently, sometimes it "stalls", sometimes it stops sending no codes at all, sometimes it sends one code only when I'm bring a tag close to the antenna or when taking it away, etc.

Initially I thought that it must be a connection problem with the antenna (like a broken soldering or cable), but I ended up soldering the antenna directly onto the RFID reader board and I got the exact same results.

//For Authorization
#include <SoftwareSerial.h>
  
SoftwareSerial RFID = SoftwareSerial(4,5);
 
char character;
String our_id;
 
void setup() {
  Serial.begin(9600);
  RFID.begin(9600);
}
  
void loop() {
   
  while(RFID.available()>0)
  {
    character = RFID.read();
    our_id += character;
  }
   
   
   if (our_id.length() > 10) {
    our_id = our_id.substring(1,13);
      if (our_id == "4800406592FF
")
      {     
        Serial.print("ACCESS GRANTED  (id: ");
        Serial.print(our_id);
        our_id = "";
        Serial.println(" ) ");
       } 
       else 
       {
        Serial.print("ACCESS DENIED   (id: ");
        Serial.print(our_id);
        our_id = "";
        Serial.println(" ) ");
      }
   }  
  
    our_id = "";
    delay(1000);
}