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Siemens  Standard application AHU  CE1P3977en_02 
Building Technologies  Functions  01.02.2010 
Main Index > Global functions > Su/Wi calculation 
Parameter  Range  Function 
State 
 
–  Winter 
–  Summer 
Status of Summer/Winter changeover: 
–  Winter operation is enabled. 
–  Summer operation is enabled. 
Su/Wi input   
 
 
 
–  Winter 
–  Summer 
Status of input on hardware side for changeover. 
Go to page with all digital input settings. For exam-
ple, you can change the input’s direction of control 
there. 
–  Winter operation enabled: Signal 0. 
–  Summer operation enabled: Signal 1. 
Outs air tmp damped    Damped outside air temperature. 
Summer date / time  *.*   *:*  Set date and time for changeover to summer op-
eration. 
Example:  
23:30    01.Apr ---> Changeover on April 1 at 11:30 
pm. 
–  Asterisks only (*.*   *:*): Changeover date is not 
relevant; changeover occurs based on tempera-
ture. 
–  Permissible time entries: 
*:* ---> 00:00 
*:20 ---> 00:20 
10:* ---> 10:00. 
–  Date entry: 
Allowed: 15.May 
Not allowed by month: Odd  / Even. 
Winter date / time  *.*   *:*  Set date and time for changeover to winter opera-
tion.  
Example: 
10:40:00 PM    01.Oct ---> Changeover on October 
1 at 10:40 pm. 
Note: See summer date / time 
Time constant   0…36000 [h]  Time constant to calculate dampened (determined 
over this period) outside air temperature. Set this 
value for the short period to 0 to reset the damp-
ened or assume present outside air temperature. 
Outs air tmp summer  -64...64 [°C]  Changes over to summer operation when the 
damped outside air temperature is greater than this 
value. 
Outs air tmp winter  -64...64 [°C]  Changes over to winter operation when the 
damped outside air temperature is less than this 
value. 
 
Parameter 
Basis Document Siemens Climatix Control System
BDCX.100820.01GB
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