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Time switch based on the S7-300/400 CPUs with simple HMI system
including radio-controlled clock connection
Rev. B - final 19.07.2002 10/84
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BID21669756_Zeitschaltuhr_einfach_DOKU_v20_e.doc
Protocol
services
S7-CPU
Monitoring and
Control unit
Process area
User program
Fig. 1-2 Problem layout for automation technology
A block in the S7-CPU, which sets an output dependent of absolute time or
which after a certain event lets a parameterized length of time pass, is
required for the temporal design of these or similar processes.
The absolute switch-on and switch-off times for these processes must be
configurable at a HMI system and subsequently be available in the S7-
CPU. Furthermore, it should be possible to parameterize a certain length of
time which will pass dependent on a start event (relative time).
The S7-CPU and the HMI system are connected via MPI.
In our example the absolute switch-on and switch-off times are entered at
the HMI system and subsequently compared with the absolute system time
of the S7-CPU.
Note
The block principally also functions without HMI interface. Parameterization can be
made directly at the input parameters.
Additionaly, the possibility of optionally connecting a radio-controlled clock
to the automation system should be offered. This clock is supposed to
synchronize the system time with the official time and to conduct the
changeover from summer time to winter time and the other way round.
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