125Khz RFID module UART - not transmitting data


I’m unable to get any serial data from this module despite making a number of attempts using an Arduino Uno Wifi.

Here is one code example:

int serialdata;

void setup()
void loop() 
  if (Serial.available() > 0) {
    serialdata = Serial.read();

Pin connections:
RFID antenna connected with red connector on P2-Pin2
RFID module P1-Pin1(tx) connected to Arduino Digital 0(rx)
RFID module P1-Pin4(gnd) connected to Arduino Power (gnd)
RFID module P1-Pin5(+5v) connected to Arduino Power (5v)

Please help? or is this a faulty module?

Hi Nicolas,

Let’s get this figured out! Before we press on, can you share a URL to the product you are referring to?

Hi Graham,

SKU: SS113990014


Hey, @Nicolas41340,
These are coil antennas - you need to connect both of the antenna wires to the P2 connector for the antenna to work. Polarity is not important.

Hope that sorts it! :smiley:

When you’re using your RFID tag, you get the best range if the tag’s coil is parallel with the RFID module’s coil - like stacking plates.

Hi Michael,

I do have both connected, as it is a single plug and can not be separated I was just pointing out which way around it was connected.

So, still no good.

Ah right, it sounded like you had only one side connected.
If that’s the case then reply to your order confirmation email, linking this forum post and we’ll get it sorted out.