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Integral Real-Time Clock
13.2
Structure of the Clock Data Area
The location of the clock data area must be stored in system data words 8 and 9. Data is always
exchanged between the control program and the integrated clock via the clock data area. The
integral clock stores current values of clock time, date and operating hours counter in the clock
data area (flag area or data block) and, in this same clock data area, the control program stores
settings for prompting times and operating hours counters. The control program can only read or
write to the clock data area, but can never access the clock direct. Figure 13-1 illustrates this
relationship.
Control
program
Read clock data with
load operations
Transfer variables with
transfer operations
Figure 13-1. Control Program and Clock Access to the Clock Data Area
When setting the clock, you need only transfer the data required for implementing the function
in question. For example, if you only want to change the data for the clock function, you need not
specify the data for the prompter function or for the operationg hours counter.
Table 13-3 gives information on the location of certain clock data within the clock data area,
regardless of the memory area selected (DB area or flag area). You will find explanations of the
entries in the clock data area following Table 13-3.
13-6
Clock data area
Current time/
current date
(words 0 to 3)
Clock time/
date settings
(words 4 to 7)
Prompter time
(words 8 to 11)
Current
operating hours
(words 12 to 14)
Operating hours
counter settings
(words 15 to 17)
Clock time /date of
the last RUN-STOP
change
(words 18 to 21)
Integral clock
Clock writes clock data to
the clock data area
Clock accepts settings from
the clock data area
EWA 4NEB 811 6130-02b
S5-115U Manual
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