Siemens Simatic S7-400 - Special Functions; Summer;Wintertime Changeover

Time switch based on the S7-300/400 CPUs with simple HMI system
including radio-controlled clock connection
Rev. B - final 19.07.2002 74/84
Copyright © Siemens AG 2005 All rights reserved
BID21669756_Zeitschaltuhr_einfach_DOKU_v20_e.doc
7.3 Special functions
The special functions “Summer/winter time changeover” and “Holidays” are
briefly discussed below.
7.3.1 Summer/wintertime changeover
For the summer/winter time changeover this application offers a program-
controlled changeover. Optionally, this time changeover can be performed
by a radio-controlled clock module (compare user interface for
summer/winter time changeover, fig. 6-7).
Standard: Program-controlled time changeover
The time changeover takes place at the last Sunday in March or
respectively at the last Sunday in October. It is checked by the block by
reading the current date/time from the S7.CPU (FB103).
Table 7-4 Configuration summer/winter time changeover (program-controlled)
Code Remarks
NETWORK 3:
L #actdate.actdayofweek // if current day of the week
sunday,
L 1
<>I
R #SetEdge
BEB // nothing -> end
L #actdate.actmonth // current month == March,
L 3
==I
SPB mrz // goto check, if it is the last sunday
L #actdate.actmonth // current month == October
L 10
==I
SPB okt // goto check, if it is the last sunday
BEA
.
.
.
Check whether today is Sunday
Check whether it is the last
Sunday in March
Check whether it is the last
Sunday in October
Option: Radio-controlled time changeover
In this case the block FB77 „DCF77_FB“ is being called instead of FB103
„summer_winter“. FB77 evaluates the signals sent by the radio-controlled
clock. The block is know-how protected, therefore only the call of the block
and the parameterization are shown below.