Do the connection by following the pinout connections mentioned in the above picture.

Here I used an Arduino UNO board along with RFID module.

Step 1: Connect LED for Indication Purpose

I'm using a visual indication i.e. LED.

Here I connected a red LED at digital pin 8 of Arduino UNO. The long pin of LED is +ve ,which is connected to digital pin 8 of Arduino UNO, and the - ve terminal will be connect to GND of Arduino UNO.

Step 2: Time Measure Using Rfid RC522

Many times you may want to record the 'ON' & 'OFF' time of machine or any equipment.

Here, we are using RFID to control access to the machine/system as well record the operation time.

Basically RFID used for turn on a system using it's UID code identification. RFID tags and keychains are used for punching the rfid reader.

What we need:

RC522 module
Jumper wire
Led(for indication)
Arduino UNO
Relay(5 volt)

Step 3: Connect the Relay

I've connect a relay for switching purpose. The " +ve terminal of DC output/ circuit " pin connect to relay connect to 5 volt of arduino UNO & "-ve terminal of DC output/ circuit" pin of the relay connect to the digital pin 4 of UNO.

COMMON and NC will link the main supply + ve terminal of supply voltage

and the supply -ve terminal will directly connect to the gnd of supply voltage.

Connect transistor emitter pin to arduino digital pin 4.

Step 4: Upload the Code

Here in this code I attach red LED +ve pin to 8 pin of Arduino UNO.

Here I'm giving 5 volt supply of relay from Arduino UNO., and connecting the relay's " relay's -ve terminal from DC supply" pin I'm connect to 4 pin of Arduino UNO.

When the digital output come from pin number 4 is 'LOW', the power supply will go to relay ; otherwise not.

Now attach this controller with your system/machine which you want to provide restricted access.