Here is the updated code.
using System; using System.Net; using System.Net.Sockets; using System.Threading; using Microsoft.SPOT; using Microsoft.SPOT.Hardware; using SecretLabs.NETMF.Hardware; using SecretLabs.NETMF.Hardware.NetduinoPlus; using System.IO; using System.Text; namespace Integration { public class Program { private const int MaximumValue = 1023; private const int AnalogReference = 5; public static void Main() { AnalogInput no2Sensor = new AnalogInput(Pins.GPIO_PIN_A0); AnalogInput coSensor = new AnalogInput(Pins.GPIO_PIN_A1); AnalogInput o3Sensor = new AnalogInput(Pins.GPIO_PIN_A2); AnalogInput e_no2Sensor = new AnalogInput(Pins.GPIO_PIN_A3); AnalogInput e_noSensor = new AnalogInput(Pins.GPIO_PIN_A4); AnalogInput e_coSensor = new AnalogInput(Pins.GPIO_PIN_A5); OutputPort led = new OutputPort(Pins.GPIO_PIN_D8, false); while (true) { int digitalValue1 = no2Sensor.Read(); float analogValue1 = (float)digitalValue1 / MaximumValue * AnalogReference; int digitalValue2 = coSensor.Read(); float analogValue2 = (float)digitalValue2 / MaximumValue * AnalogReference; int digitalValue3 = o3Sensor.Read(); float analogValue3 = (float)digitalValue3 / MaximumValue * AnalogReference; int digitalValue4 = e_no2Sensor.Read(); float analogValue4 = (float)digitalValue4 / MaximumValue * AnalogReference; int digitalValue5 = e_noSensor.Read(); float analogValue5 = (float)digitalValue5 / MaximumValue * AnalogReference; int digitalValue6 = e_coSensor.Read(); float analogValue6 = (float)digitalValue6 / MaximumValue * AnalogReference; Debug.Print("NO2 value:\t" + analogValue1.ToString() + "\nCO Value:\t" + analogValue2.ToString() + "\nO3 Value:\t" + analogValue3.ToString() + "\ne_NO2 value:\t" + analogValue4.ToString() + "\ne_NO Value:\t" + analogValue5.ToString() + "\ne_CO Value:\t" + analogValue6.ToString()); using (StreamWriter sw = new StreamWriter(@"SD\file.csv", true)) { sw.Write(analogValue1.ToString() + "," + analogValue2.ToString() + "," + analogValue3.ToString() + "," + analogValue4.ToString() + "," + analogValue5.ToString() + "," + analogValue6.ToString()); sw.Write("\n"); sw.Flush(); sw.Close(); } led.Write(true); Thread.Sleep(295); led.Write(false); Thread.Sleep(50); } } } }