EM-18 RFID READER

                              This module directly connects to any microcontroller UART or through a RS232 converter to PC.It gives UART/Wiegand26 output. This RFID Reader Module works with any 125 KHz RFID tags.

Specifications

•    5VDC through USB (External 5V supply will boost range of the module)
•    Current: <50mA
•    Operating Frequency: 125Khz
•    Read Distance: 10cm
•    Size of RFID reader module: 32mm(length) * 32mm(width) * 8mm(height)

RS232 interface format

10 ASCII DATA (card no.)+ 2 ASCII DATA (XOR result)

E.g. Card number is 4500C5D1E9B8 read from reader then the card number on card will be as below.

45 - Preamble

00C5D1E9 value in Hex = 12964329. / B8 is XOR value for (45 XOR 00 XOR C5 XOR D1 XOR E9)

Hence number on the card is 0012964329.

1. Data baud rate: 9600 bps
2. Data bit 8 bits
3. Parity check: None
4. Stop bit

he EM-18 RFID Reader communicates over UART (TTL Serial) with the following settings:

• Baud Rate: 9600 bps
• Data Bits: 8
• Parity: None
• Stop Bits: 1
• Flow Control: None (8N1)

UART Data Format

When a tag is detected, the EM-18 transmits:

10 ASCII characters (Tag ID) + 2 ASCII characters (Checksum)

Total transmitted data:

12 ASCII bytes

Many modules also send framing characters:

Some EM-18 modules output only the 12 ASCII bytes, while others include STX (0x02) at the beginning and ETX (0x03) at the end.

Example

Suppose the RFID tag ID is:

4500C5D1E9

The UART output will be:

45 30 30 43 35 44 31 45 39 B8

or, as ASCII:

4500C5D1E9B8

where:

• 4500C5D1E9 = 10-character RFID ID
• B8 = 2-character XOR checksum of the first 10 characters

Timing

After a card is presented:

1. Reader detects the tag.
2. Sends the complete UART frame once.
3. Stops transmitting until another tag is detected.

Receiving with a Microcontroller

Read 12 bytes (or 14 bytes if your module includes STX/ETX) from the UART RX pin.

Example frame:

02 34 35 30 30 43 35 44 31 45 39 42 38 03
│  └──────────── Tag ID ────────────┘ └Checksum┘ │
STX                                              ETX