[EHaskins]

The easiest way to do this is to increment a variable every time you get new data from the master processor.

Default Autonomous:

  while (autonomous_mode)   /* DO NOT CHANGE! */
  {
    if (statusflag.NEW_SPI_DATA)      /* 26.2ms loop area */
    {
        Getdata(&rxdata);   /* DO NOT DELETE, or you will be stuck here forever! */

        /* Add your own autonomous code here. */

        Generate_Pwms(pwm13,pwm14,pwm15,pwm16);

        Putdata(&txdata);   /* DO NOT DELETE, or you will get no PWM outputs! */
    }
  }

The first thing you need to do is create a static variable to use as a counter.

static int i;

Then you need to increment the variable. The easiest way to do this is to increment the counter each time you get new data.

  while (autonomous_mode)   /* DO NOT CHANGE! */
  {
    if (statusflag.NEW_SPI_DATA)      /* 26.2ms loop area */
    {
        Getdata(&rxdata);   /* DO NOT DELETE, or you will be stuck here forever! */

        i++; // this will increment the 'i' variable by 1.

        /* Add your own autonomous code here. */

        Generate_Pwms(pwm13,pwm14,pwm15,pwm16);

        Putdata(&txdata);   /* DO NOT DELETE, or you will get no PWM outputs! */
    }
  }

Now you can calculate the time by multiplying the time span(26.2) by the number if times(i) to get the actual time.

int time;

  while (autonomous_mode)   /* DO NOT CHANGE! */
  {
    if (statusflag.NEW_SPI_DATA)      /* 26.2ms loop area */
    {
        Getdata(&rxdata);   /* DO NOT DELETE, or you will be stuck here forever! */
        i++; // this will increment the 'i' variable by 1.
        time =  (i * 262)/2500 // if you avoid the decimal, by multiplying the time span by 10, your code will execute faster because it will not use a floatig points.
        // I divide the time(in 10000enths of a second) by 2500 so I get a result in 1/4 of a second

        Generate_Pwms(pwm13,pwm14,pwm15,pwm16);

        Putdata(&txdata);   /* DO NOT DELETE, or you will get no PWM outputs! */
    }
  }

Example code to drive forward 1 second, then reverse for 1 second.

int time;

  while (autonomous_mode)   /* DO NOT CHANGE! */
  {
    if (statusflag.NEW_SPI_DATA)      /* 26.2ms loop area */
    {
        Getdata(&rxdata);   /* DO NOT DELETE, or you will be stuck here forever! */
        i++; // this will increment the 'i' variable by 1.
        time =  (i * 262)/2500 // if you avoid the decimal, by multiplying the time span by 10, your code will execute faster because it will not use a floatig points.
        // I divide the time(in 10000enths of a second) by 2500 so I get a result in 1/4 of a second

        //drive code\\
        if (time < 4) pwm01 = pwm02 = 255; //forward
        else if(time < 8) pwm01 = pwm02 = 0; //reverse
        else if(time > 8) pwm01 = pwm02 = 127;//stop

        Generate_Pwms(pwm13,pwm14,pwm15,pwm16);

        Putdata(&txdata);   /* DO NOT DELETE, or you will get no PWM outputs! */
    }
  }

I think that is what your looking for.

Hope this helps, and sorry for the long post.