Procedure for the experiment is as follows:

1. Open the experiment in the virtual lab for interfacing multiple sensors.
   The Arduino board and all sensors (Ultrasonic, PIR, DHT, Soil Moisture, MQ135) are already connected in the workspace.

2. Observe the circuit connections.
   Check how each sensor is wired with the Arduino pins.
   Identify trigger/echo pins for Ultrasonic, output pin for PIR, data pin for DHT, analog signal pin for Soil Moisture, and analog/digital output for MQ135.

3. Open and review the Arduino code.
   Read the predefined code to understand how each sensor is initialized and how readings are taken.
   Observe the logic used for distance measurement, motion detection, temperature/humidity reading, soil moisture levels, and gas sensor values.

4. Start the simulation.
   Click the "Start Simulation" button.
   Observe real-time data from all sensors displayed on the Serial Monitor.
   Trigger the PIR sensor, change soil moisture values, vary gas concentration, or adjust distance for the Ultrasonic sensor (as per simulation options).

5. Interact with the simulation if required.
   Some sensors may show varying values based on simulation controls such as sliders or environment presets.

6. Record observations.
   Note the sensor readings for all five sensors and how they change during simulation.

7. Stop the simulation.
   Click the "Stop Simulation" button after completing the experiment.