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Time is recorded in a data file much like any other data source. The purpose of the Time Data Format 1 packet is to provide a correlation between an external clock source and the recorder internal 10 MHz RTC. The correlation between the RTC and clock time is described in more detail in paragraph 6.6.

The time data packet begins with the CSDW shown in Figure 6-18.

struct SuTimeF1_ChanSpec 
    { 
    uint32_t    uTimeSrc    :  4;   // Time source 
    uint32_t    uTimeFmt    :  4;   // Time format 
    uint32_t    bLeapYear   :  1;   // Leap year 
    uint32_t    uDateFmt    :  1;   // Date format 
    uint32_t    uReserved1  :  2; 
    uint32_t    uReserved2  : 16; 
    }; 

The uTimeSrc field indicates the source is for the time used. Note that this field changed slightly between the 2004 and the 2005 release of Chapter 10. The uTimeFmt field is used to indicate the nature and type of the source of external time source applied to the recorder. The uDataFmt field is used to determine how to interpret the time data that follows. Time representation in Day (i.e. Day of the Year) format is shown in Figure 6-19. Time representation in Day-Month-Year format is shown in Figure 6-20. The bLeapYear field in the CSDW is useful to convert Day of the Year to Day and Month when the year is not known.

// Time message - Day format 
struct SuTime_MsgDayFmt 
    { 
    uint16_t    uTmn        : 4;    // Tens of milliseconds 
    uint16_t    uHmn        : 4;    // Hundreds of milliseconds 
    uint16_t    uSn         : 4;    // Units of seconds 
    uint16_t    uTSn        : 3;    // Tens of seconds 
    uint16_t    Reserved1   : 1;    // 0 
    uint16_t    uMn         : 4;    // Units of minutes 
    uint16_t    uTMn        : 3;    // Tens of minutes 
    uint16_t    Reserved2   : 1;    // 0 
    uint16_t    uHn         : 4;    // Units of hours 
    uint16_t    uTHn        : 2;    // Tens of Hours 
    uint16_t    Reserved3   : 2;    // 0 
    uint16_t    uDn         : 4;    // Units of day number 
    uint16_t    uTDn        : 4;    // Tens of day number 
    uint16_t    uHDn        : 2;    // Hundreds of day number 
    uint16_t    Reserved4   : 6;    // 0 
    }; 

// Time message - DMY format 
struct SuTime_MsgDmyFmt 
    { 
    uint16_t    uTmn        : 4;    // Tens of milliseconds 
    uint16_t    uHmn        : 4;    // Hundreds of milliseconds 
    uint16_t    uSn         : 4;    // Units of seconds 
    uint16_t    uTSn        : 3;    // Tens of seconds 
    uint16_t    Reserved1   : 1;    // 0 
    uint16_t    uMn         : 4;    // Units of minutes 
    uint16_t    uTMn        : 3;    // Tens of minutes 
    uint16_t    Reserved2   : 1;    // 0 
    uint16_t    uHn         : 4;    // Units of hours 
    uint16_t    uTHn        : 2;    // Tens of Hours 
    uint16_t    Reserved3   : 2;    // 0 
    uint16_t    uDn         : 4;    // Units of day number 
    uint16_t    uTDn        : 4;    // Tens of day number 
    uint16_t    uOn         : 4;    // Units of month number 
    uint16_t    uTOn        : 1;    // Tens of month number 
    uint16_t    Reserved4   : 3;    // 0 
    uint16_t    uYn         : 4;    // Units of year number 
    uint16_t    uTYn        : 4;    // Tens of year number 
    uint16_t    uHYn        : 4;    // Hundreds of year number 
    uint16_t    uOYn        : 2;    // Thousands of year number 
    uint16_t    Reserved5   : 2;    // 0 
    }; 

Reserved for future use