Specifications

IP 240 Position Decoding
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.
FB 170
: SPA FB 170
NAME: STEU.WEG
DBNR : KF
FKT : KF
PAFE : QB
DBNR
FKT PAFE
LAD/CFSSTL
QB
Table 7-6. Parameters for Control FB 170
Name Para- Data Description
meter type
type
DBNR D KF Data block number
FKT D KF Function number
PAFE Q BY Error identifier byte
Parameter assignments
DBNR : KF 3 to 255 Number of the data block created
FKT : KF 1 Read actual value and status bits
2 Write control statements (control bits)
3 Read interrupt request bytes
4 Write initial and final track values
5 Write zero offset
PAFE : QB Flag byte or output byte in which errors are to be flagged
( Section 6.4).
EWA 4NEB 811 6120-02a 7-23