User Manual

Calendars and schedulers
Schedule
10
170 | 353 CM110664en_07
Effective period [EfPrd]
You can define the period for which the schedule is to be active, e.g., you can
configure separate schedules for summer and winter operation. If the current
day is outside the active period, the [PrVal] output is equal to the default value
[DefVal].
Time resolution
The smallest unit in the scheduler program is one minute and in the calendar
one day. The schedule may be dependent on the calendar. In the PX
automation stations, the calendar function block is automatically processed
before the scheduler function block. The superposed cycle for processing the
calendar and scheduler begins at the start of the new minute of the system
time.
A PX automation station incorporates an automatic load shedding mechanism.
The result is that a switch command at time x is executed within a time-period
defined by time x + 1 minute.
System time
Schedules and calendars are based on the same global time. This ensures that
all automation stations on a site have the same time base.
Interdependency and order of processing
The calendar and schedule function blocks are standalone objects which are
processed individually. The Schedule function blocks depend on the Calendar
function blocks. The objects to be switched (commanded objects or data flow
output) depend on the Schedule function blocks.
At start-up, when delta loading and when adjusting the date and time, the order
of processing is a key factor in ensuring that from the first processing cycle on,
the correct output values of a schedule function block are determined and
transmitted to the output. The temporary transmission of incorrect switch
values can be avoided in this way. The order of processing of the individual
function blocks is determined in the CFC Editor (manual/automatic).
The order of processing is:
1. Calendar function blocks
2. Schedule function blocks
3. Any other function blocks, which could be switched by a schedule function
block
Interdependency of
function blocks
Processing order