Siemens SIMATIC S5 Manual page 254

Application of the Function Block
The DB type and DB number entered in data word DW4 must agree with the DB type and DB
number of the data block opened when FB 162 is called.
The number of DB-A' can be between 10 and 254. DB-A' and DB-C' must not overlap with DB-A,
DB-B and DB-C.
E.g. data block
If function block FB 162 is called with indirect parameter assignment, the data areas shown in bold
face must be assigned before calling the FB. Data word DW1 is then cleared by FB 162 as soon
as the entered command has been executed (DW 1 = KH0000). If a parameter assignment error
occurs while the command is being processed, the command in DW 1 is once again cleared. A new
command can now be entered (acknowledgement to the user program)
Indirect parameter assignment
5–50
DB 170 or DX 170
DW 0 : KH0000 DW 0 : KH0000
DW 1 : KS DW 1 : KS
DW 2 : KY DW 2 : KY
DW 3 : KF DW 3 : KF
DW 4 : KY 0,170 DW 4 : KY 1,170
IP244
C79000–B8576–C861–02