Hitachi

JP1 Version 12 JP1/Automatic Operation Administration Guide 


A.2 Using JP1/AO in time zones that observe daylight saving time

When you use JP1/AO in a time zone that observes daylight saving time, the following start times are affected:

The explanation below uses the example of Central Daylight Time (USA and Canada). The start and end times for CDT are as follows:

Organization of this subsection

(1) Transitioning from standard time to daylight saving time

The timing with which tasks start after the system switches from standard time to daylight saving time is determined from the start time set for the task, and the time difference between standard and daylight saving time. When the clock reaches what would be 2:00:00 on the second Sunday in March, it instead jumps to 3:00:00. This means that the time from 2:00:00 to 2:59:59 is skipped over. If you set up a task to start within this period, it will start between 3:00:00 and 3:59:59 daylight saving time. This means that the task will start an hour later in relative terms.

If you set up a task to start at 3:00:00 or later while in standard time, it will still start at 3:00:00 or later after the transition to daylight saving has taken place.

The following table shows how tasks are scheduled around the transition from standard time to daylight saving time:

Table A‒2: Scheduling at the transition from standard time to daylight saving time

Scheduled start time

1:59:59 or earlier

2:00:00 to 2:59:59

3:00:00 or later

Actual start time

Executed at 1:59:59 or earlier standard time

Executed at 3:00:00 to 3:59:59 daylight saving time

Executed at 3:00:00 or later daylight saving time

(2) Transitioning from daylight saving time to standard time

The timing with which tasks start after the system switches from daylight saving time to standard time is determined from the start time set for the task, and the time difference between standard and daylight saving time. When the time reaches what would be 2:00:00 on the first Sunday of November, the clock jumps back to 1:00:00 standard time. The result is an extra hour after switching to standard time, from 1:00:00 to 2:00:00. Tasks that were scheduled to start between 1:00:00 and 1:59:59 start at the scheduled time while still in standard time, and do not start in daylight saving time. If you schedule a task to start at 2:00:00 or later while in daylight saving time, it will still start at 2:00:00 or later after the transition to standard time has taken place.

The following table shows how tasks are scheduled around the transition from daylight saving time to standard time:

Table A‒3: Scheduling at the transition from daylight saving time to standard time

Scheduled start time

0:59:59 or earlier

1:00:00 to 1:59:59

2:00:00 or later

Actual start time

Executed at 0:59:59 or earlier daylight saving time

Executed between 1:00:00 and 1:59:59 standard time

Executed at 2:00:00 or later standard time