Useofthe Function Block - Siemens SIMATIC S5 Equipment Manual

9.4.7 Use of the Function Block
The module must be parameterized with function block FB 156 before function block FB 158 can
be called.
The parameter transfer is performed via the working data block. The function to be executed by
function block FB 158 is selected by entering the appropriate command code in format KS in data
word DW n.
Before a new command is entered in data word DW n in the working data block, a check must be
performed to determine whether the contents have been deleted by function block FB 158 (DW n
KH = 0000). The procedure is shown in the following pictogram.
Contents of data word DW n in working data block equal zero?
Yes
Write new command in DW n
Calling function block FB 158 with KH = 0000 in data word DW n of the working data block causes
the block to be exited without triggering a function (idling).
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I
Call function block FB 158
Programming Instructions
No
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