Generic RFID 125 kHz reader

Years ago I did buy a small and inexpensive 125 kHz RFID reader.
This article would be a kind of datasheet/notes of this reader and suggestions about how to use it.

The reader has no brand indication, must be some Chinese clone.
I did find a similar item online : Mini-125Khz-RFID-Module-Antenna-35mm-Wiegand-Protocol 
also available on Seed.
Some info about how to interface the reader are available from an Arduino library (from Seed).

Pinout

The reader has 6 pins :

1. Vcc  --> 3.3V or 5V
2. Gnd
3. Tx   -->  Data output serial TTL (9600 baud)
4. Rx
5. W0  --> Wiegand protocol
6. W1  --> Wiegand protocol

In order to work need to be interfaced with a UART using the Tx and Rx and GND.
The module supports a TTL serial output and a Wiegand protocol output.

The typical connection uses just the pin 3 (Tx) interfaced with a controller.

Testing

In order to test the module I did resurrect a very old experimental platform I did built in the 1998 :) and is still amazingly working.

The platform has some breadboards, a power supply and wave generator plus a bunch of LED and switches.
Actually I just needed a breadboard and a power supply but who knows where I put this stuff, so .. experimental platform it is !

Powered the module with 5V, noticed the Tx line going high and that's it.
Passing various RFID cards I know NOT to be 125Khz ones I had around, no activity at all did show on the Tx pin (monitored with an oscilloscope). 
Passing some 125 Khz RFID card I immediately noticed activity.

Oscilloscope screenshots of a 125 Khz reading on the Tx pin

Data format

The module is sending out a serial ID when a valid 125 kHz RFID card is detected.
The RFID library for Arduino uses the SoftwareSerial library capable to simulate an UART using generic I/O pins.
Arduino libraries assumes to use an 8N1 format for every byte, so this is the main assumption for the SerialSoftware library and thus the output of the RFID reader.