Control Function Block - Siemens Simatic S5 IP 240 Manual

IP 240
7.3.2

Control Function Block

FB 170 (STEU.WEG) Control function block for position decoding mode.
Functional description
The control function block first verifies whether the addressed channel has been configured for
the "position decoding" mode. In accordance with the parameter assignments of the function
block, certain data areas are then transferred from the data block to the IP 240 or updated in the
DB by reading them from the IP 240.
The following functions are possible:
• Reading the actual value and the status bits
• Writing the control statements (control bits)
• Reading the interrupt request bytes
• Writing the initial and final track values
• Writing the zero offset
Communications and parameter errors are flagged in the PAFE byte and described in detail in
data words DW 8 to 10 and DW 13. The specified function is not executed in the event of an error.
Function block call
The control FB is usually called in the cyclic program part and in the interrupt organization blocks.
: SPA FB 170
NAME : STEU.WEG
DBNR : KF
FKT : KF
PAFE : QB
Name Para-
meter
type
DBNR D
FKT D
PAFE Q
Parameter assignments
DBNR : KF 3 to 255
FKT : KF 1
2
3
4
5
PAFE : QB
EWA 4NEB 811 6120-02a
STL
Table 7-6. Parameters for Control FB 170
Data Description
type
KF Data block number
KF Function number
BY Error identifier byte
Number of the data block created
Read actual value and status bits
Write control statements (control bits)
Read interrupt request bytes
Write initial and final track values
Write zero offset
Flag byte or output byte in which errors are to be flagged
( Section 6.4).
Position Decoding
LAD/CFS
FB 170
DBNR
FKT PAFE QB
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