Siemens SIMATIC S7-300 FM 350-1 Manual page 52

Programming the FM 350-1
5.5 Application example
Description of the Procedure
The load value of the channel is transferred to the FM 350-1 by means of the function call.
When calling the CNT_CTL1 function, select either the L_DIRECT parameter or the
L_PREPAR parameter.
Parameter L_DIRECT defines that the load value is transferred directly and in preparation to
the counter (you set the trigger bit L_DIRECT=1 in your user program).
Parameter L_PREPAR defines that the load value is only loaded in preparation (you have to
set the trigger bit L_PREPAR=1 in your user program).
The load value loaded in preparation is then applied at the next cause that sets the counter.
The FC must therefore be called until the FC has reset the selected trigger bit (L_DIRECT or
L_PREPAR). The in/out parameter remains set during the transfer. The CNT_CTL1 function
does not issue an error message with regard to the exchange of data with the FM.
If the trigger bit you set has been reset by the CNT_CTL1 function, the FM 350-1 has applied
the load value. The read load value stored in DB 1 is updated by the CNT_CTL1 function
(applicable only if you are working without the latch setting).
It takes at least four FC calls to transfer the load value.
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FM 350-1 Counter module
Manual, 05/2011, A5E03648639-01