Time switch based on the S7-300/400 CPUs with simple HMI system
including radio-controlled clock connection
Rev. B - final 19.07.2002 38/84
Copyright © Siemens AG 2005 All rights reserved
BID21669756_Zeitschaltuhr_einfach_DOKU_v20_e.doc
4.3.7 Additional functions
In addition to the blocks for the absolute time switch and the relative time
switch, blocks for summer/winter time changeover as well as for holiday
recognition are also supplied.
Summer/wintertime changeover
Standard: Program controlled (FB 103 “summer_winter”)
The block for the summer/winter time changeover adds exactly 1 hour to
the current system time in the S7-CPU, when changing from winter to
summer time, and subtracts exactly 1 hour when changing from summer to
winter time. Changeover from winter to summer time occurs at the last
Saturday in March, from summer to winter time at the last Saturday in
October.
The block has the following input parameter:
• active of “BOOL“ type
If the parameter = 1, the block is executed. If the parameter = 0,
executing the block is prevented.
The block has the following output parameters:
• summertime of “BOOL“ type
Value = 1: It is summer time
Value = 0: It is winter time
• Error of “INT“ type
Not equal 0, if during processing an error has occurred.
The block for the summer/winter time changeover “summer_winter” FB103
is parameterized as illustrated in the figure below. Data block DB103 is
used as instance data block:
Fig 4-11 Configuration “summer/winter time changeover”
Basic data
RAM requirements:
summer_winter: 382 bytes
Instance DB: 48 bytes
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