# 125Khz RFID module UART - not transmitting data

**URL:** <https://forum.core-electronics.com.au/t/125khz-rfid-module-uart-not-transmitting-data/1141>\
**Category:** Seeed Studio\
**Created:** [20 June 2017 06:14 UTC](https://forum.core-electronics.com.au/t/125khz-rfid-module-uart-not-transmitting-data/1141 "2017-06-20T06:14:25Z")\
**Posts on this page:** 6\
**Page:** 1

<div class="post-metadata">

**Author:** ![Nicolas41340](https://avatars.discourse-cdn.com/v4/letter/n/ac8455/32.png) [@Nicolas41340](https://forum.core-electronics.com.au/u/Nicolas41340)\
**Post date:** [20 June 2017 06:14 UTC](https://forum.core-electronics.com.au/t/125khz-rfid-module-uart-not-transmitting-data/1141/1 "2017-06-20T06:14:25Z")

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Hi,

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()
{
  Serial.begin(9600);
  Serial.println("ready");
}
void loop() 
{
  if (Serial.available() > 0) {
    serialdata = Serial.read();
    Serial.println(serialdata);
  }
}

```

* * *

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?**

---

<div class="post-metadata">

**Author:** ![Graham](https://yyz2.discourse-cdn.com/flex028/user_avatar/forum.core-electronics.com.au/graham/32/54_2.png) [@Graham](https://forum.core-electronics.com.au/u/Graham)\
**Post date:** [20 June 2017 06:50 UTC](https://forum.core-electronics.com.au/t/125khz-rfid-module-uart-not-transmitting-data/1141/2 "2017-06-20T06:50:42Z")

</div>

Hi Nicolas,

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

---

<div class="post-metadata">

**Author:** ![Nicolas41340](https://avatars.discourse-cdn.com/v4/letter/n/ac8455/32.png) [@Nicolas41340](https://forum.core-electronics.com.au/u/Nicolas41340)\
**Post date:** [20 June 2017 07:19 UTC](https://forum.core-electronics.com.au/t/125khz-rfid-module-uart-not-transmitting-data/1141/3 "2017-06-20T07:19:44Z")

</div>

Hi Graham,

SKU: SS113990014

> **[125Khz RFID module - UART (Seeed Studio)](https://core-electronics.com.au/125khz-rfid-module-uart-seeed-studio.html)**
>
> One of the coolest part of IoT project must be the identification technology, 125Khz RFID module – UART is the most popular RFID module that produced by .. read more

Regards,  
Nicolas

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<div class="post-metadata">

**Author:** ![Michael\_R](https://yyz2.discourse-cdn.com/flex028/user_avatar/forum.core-electronics.com.au/michael_r/32/435_2.png) [@Michael\_R](https://forum.core-electronics.com.au/u/Michael_R)\
**Post date:** [21 June 2017 06:01 UTC](https://forum.core-electronics.com.au/t/125khz-rfid-module-uart-not-transmitting-data/1141/4 "2017-06-21T06:01:23Z")

</div>

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! 😃

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.

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<div class="post-metadata">

**Author:** ![Nicolas41340](https://avatars.discourse-cdn.com/v4/letter/n/ac8455/32.png) [@Nicolas41340](https://forum.core-electronics.com.au/u/Nicolas41340)\
**Post date:** [21 June 2017 06:14 UTC](https://forum.core-electronics.com.au/t/125khz-rfid-module-uart-not-transmitting-data/1141/5 "2017-06-21T06:14:50Z")

</div>

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.

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<div class="post-metadata">

**Author:** ![Michael\_R](https://yyz2.discourse-cdn.com/flex028/user_avatar/forum.core-electronics.com.au/michael_r/32/435_2.png) [@Michael\_R](https://forum.core-electronics.com.au/u/Michael_R)\
**Post date:** [21 June 2017 06:37 UTC](https://forum.core-electronics.com.au/t/125khz-rfid-module-uart-not-transmitting-data/1141/6 "2017-06-21T06:37:21Z")

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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.