Day and Time comparison S7

Nepiter

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Join Date
Apr 2010
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At job
Posts
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I'm using S7-317 cpu's SFC1 function, and having some questions about that area..

I need to set bit at 9.00 and reset bit 18.30.

For that, I have converted time from SFC1 (db1.dbw3 hh:mm) BCD->INT .
Also I have converted set-time and reset time BCD->INT.
Now I should be able to compare time.

But I have small problem:

When I convert BCD to INT, time 18.30 is same as 8.30.
time 18.30 = hex:1830, INT:830
time 08.30 = hex:0830, INT:830

So, my comparison does not work that way.
Any ideas what is wrong?

P.S. Any ideas why my Date and Time will not give a day of week at byte 8? It is changing rapidly between 25 and 66.
 
Last edited:
Use FC8 from the standard library>IEC functions to extract the time of day from the date and time, you can then do your comparisons.

Example function block:

Code: 
FUNCTION_BLOCK FB 1
TITLE =
VERSION : 0.1


VAR_IN_OUT
  bBitToControl : BOOL ;    
END_VAR
VAR
  bSetEdgeStore : BOOL ;    
  bResetEdgeStore : BOOL ;    
END_VAR
VAR_TEMP
  datDateAndTime : DATE_AND_TIME ;    
  iSFC1ReturnValue : INT ;    
  todTimeOfDay : TIME_OF_DAY ;    
END_VAR
BEGIN
NETWORK
TITLE =

      CALL SFC    1 (
           RET_VAL                  := #iSFC1ReturnValue,
           CDT                      := #datDateAndTime);

      CALL FC     8 (
           IN                       := #datDateAndTime,
           RET_VAL                  := #todTimeOfDay);

      A(    ; 
      L     #todTimeOfDay; 
      L     T#9H; 
      >D    ; 
      )     ; 
      FP    #bSetEdgeStore; 
      S     #bBitToControl; 

      A(    ; 
      L     #todTimeOfDay; 
      L     T#18H30M; 
      >D    ; 
      )     ; 
      FP    #bResetEdgeStore; 
      R     #bBitToControl; 

      SET   ; 
      SAVE  ; 
END_FUNCTION_BLOCK
 
Many thanks!
That solved the problem with time comparison!

If any ideas with byte 8 (day of week) I would be interested.
 
in Byte 7 with the 4 "Most Significant Bits" (MSB) for milliseconds and the 4 "Last Significant Bits" (LSB) for day of week

Day of week:
1: Sunday,
2: Monday,
3: Tuesday,
4: Wednesday,
5: Thursday,
6: Friday,
7: Saturday
Datum_Uhrzeit_mit_SFC_ein_u_auslesen_01_e.gif
 
Last edited:

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