DateTime Clock

This example shows how the calendar representation of a DateTime signal corresponds to its stored value for each value of the Time point parameter.

For more information on the allowed values of the Time point parameter, see the DateTime Clock block documentation.

Both DateTime Clock blocks in "Area A" of model ex_datetime_clock_block_time_points are set to 12:00 AM UTC, January 1, 1970 at simulation time 0. This is the UNIX epoch, the time at which DateTime Clock blocks with Time point set to Seconds since Unix epoch output a stored value of 0. This value is interpreted differently depending on whether the DateTime Clock block's Time standard is set to TAI or UTC. The UTC clock block reads 01-Jan-1970 00:00:00, while the TAI clock block accounts for a 10-second offset between TAI and UTC at the inception of UTC and reads 01-Jan-1970 00:00:10.

All DateTime Clock blocks in "Area B" of model ex_datetime_clock_block_time_points are set to 12:00 PM UTC, January 1, 2000 at simulation time 0. The TAI clock readings are exactly 32 seconds ahead of the UTC clocks. The TT clock readings are 64.184 seconds ahead of the UTC clocks, which is truncated to 64 seconds by the Display block.

Time points can be split into two categories:

model='ex_datetime_clock_block_time_points';
load_system(model)
sim(model);
open_system(model)

This example shows the behavior of three DateTime Clock blocks with Time standard set to UTC. Each block steps through the leap second that occurred on December 31, 2016.

The first block's Account for new leap seconds after simulation start parameter is cleared. This block ignores the leap second and immediately rolls over to January 1, 2017 (Display block).

The second block's Account for new leap seconds after simulation start parameter is selected and its Output DateTime as bus with leap second indicator parameter is cleared. During the leap second, this block repeats the preceding 23:59:59 second (Display1 block).

The third block's Account for new leap seconds after simulation start and Output DateTime as bus with leap second indicator parameters are both selected. This block outputs a two-element virtual bus whose first element is a DateTime signal and whose second element is a boolean signal. Use a Bus Selector block to separate the virtual bus into its constituent signals. During a leap second, the DateTime signal repeats the preceding 23:59:59 timestamp (Display3 block) and the boolean signal is true (Display4 block). The DateTime to Formatted String block accepts the virtual bus as input and treats it as a DateTime signal with a 23:59:60 timestamp (Display2 block).

model='ex_datetime_clock_block_leap_seconds';
load_system(model)
sim(model);
open_system(model)