I am trying to get my Arduino Uno to read multiple temperature sensors. I have it reading one and and outputting the time, but the second sensor keeps reading 0.00. The code is below. I have no idea why this is happening. I would appreciate any help. Thank you!

Sample Output:

1. import processing.serial.*;
3. 
   
4. PFont myFont;     // The display font:
5. String inString;  // Input string from serial port:
6. int lf = 10;      // ASCII linefeed 
7. PrintWriter output;
8. DateFormat fnameFormat= new SimpleDateFormat("yyMMdd_HHmm");
9. DateFormat  timeFormat = new SimpleDateFormat("hh:mm:ss");
10. String fileName;
11. Serial myPort;        // Create object from Serial class
12. short portIndex = 0;  // select the com port, 0 is the first port;
13. long timeold = 0;
14. int interval = 500;
15. int linefeed = 10;   // Linefeed in ASCII
16. 
    
17. void setup()
18. { 
19.   // Open whatever serial port is connected to Arduino.
20.   String portName = Serial.list()[portIndex];
21.   println(Serial.list());
22.   println(" Connecting to -> " + Serial.list()[portIndex]);
23.   myPort = new Serial(this, portName, 9600);
24.   Date now = new Date();
25.   fileName = fnameFormat.format(now);
26.   output = createWriter(fileName + ".csv"); // save the file in the sketch folder
27.   background(50);
28.   myPort.bufferUntil(linefeed);
29. }
30. 
    
31. 
    
32. void draw()
33. {
34.   int val;
35.   String time;
36. 
    
37.   while ( myPort.available() >= 15)  // wait for the entire message to arrive
38.   {
39.       long currentTime = millis();
40.       if(currentTime - timeold > interval) {
41.         String inString = myPort.readStringUntil('\n');
42.         String[] words = split(inString, '\t');
43.         String temp = words[0];
44.         println(temp);
45.         output.print(currentTime / 1000.0);
46.         output.print(", ");
47.         output.println(temp);
48.       
49.       }
50. }
51. }
52.   
53.   void keyPressed() {
54.   output.flush(); // Writes the remaining data to the file
55.   output.close(); // Finishes the file
56.   exit(); // Stops the program
57.   }