Siemens SIMATIC S7 400 Application Description page 11

Time switch based on the S7-300/400 CPUs with simple HMI system
including radio-controlled clock connection
This application was realized with the SIPLUS radio clock. Alternatively the
SICLOCK radio clock can be used. This alternative is dealt with in detail in
the appendix.
In case you do not want to use a radio-controlled clock the summer/ winter
time changeover is automatically conducted at the officially fixed dates by a
special function block which is delivered with this application. In this case
the system time can certainly not be synchronized with the official time.
Basic data of the requirement
The requirements by the automation problem on the S7-CPU and the HMI
interface are listed below:
S7 CPU
• There are the following blocks:
- One-day, seven-day, one-month, one-year time switches
- Relative time switch
- Summer/wintertime changeover
- Holiday recognition
- Connection with radio-controlled clock
• Respectively one switch-on and one switch-off time can be
parameterized for the time switches (one-day, seven-day, one-month,
one-year and relative time switch).
• Resetting the time switches must be simple.
HMI Interface
User interface for the application for
• Input for current switch-on and switch-off times
• Controlling the sample application:
Starting / resetting time switches
• Display of current time switch status (on/off)
• Button for selecting mode of summer / winter time changeover: via radio-
controlled clock or via function block (delivered with the application)
Rev. B - final 19.07.2002
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