Siemens SIMATIC S5 Manual page 253

Calling the function block
The function block can be called absolutely in the cyclic program.
In this case, it is advisable to use indirect parameter assignment. For this, the parameter DBNR
must be assigned the value KY = 0.0 and the required parameters written to data block DB-A, DW1
to DW8 and DW12 to DW 13.
The function block may only be called once per temperature controller module per cycle.
When calling FB162, you can decide whether to use direct or indirect parameter assignment. Once
the mode of parameter assignment has been selected, this must be adhered to for all further FB
calls for the same IP module.
Indirect parameter assignment uses the working area of DB-A (DW0 to DW15):
Application with indirect parameter assignment
You will find the explanation of the data words under the parameters of the FB in direct parameter
assignment (Sections 3.2 and 3.3) and on the following pages in this Chapter.
IP244
C79000–B8576–C861–02
Application of the Function Block
5–49