Detailed description
2.12 Block descriptions
Basic logic functions: PLC Basic program powerline (P3 pl)
202 Function Manual, 11/2006, 6FC5397-0BP10-2BA0
2.12.17 FC 12: AUXFU call interface for user with auxiliary functions
Description of functions
FC AUXFU is generally called on an eventdriven basis in the basic program if the channel
transferred in the input parameter contains new auxiliary functions. The PLC user can extend
FC AUXFU with program instructions for processing his auxiliary function to avoid cyclic
polling of the channel DBs. This mechanism permits auxiliary functions to be processed on a
jobdriven basis. FC AUXFU is supplied as a compiled empty block in the basic program. In
this case, the basic program supplies parameter "Chan" with the channel number. The PLC
user knows which channel has new auxiliary functions available. The new auxiliary functions
can be determined by the auxiliary-function change signals in the channel concerned.
Declaration of the function
FUNCTION FC 12: VOID
//Event control of auxiliary functions
VAR_INPUT
Chan: BYTE ;
END_VAR
BEGIN
BE;
END_FUNCTION
Explanation of formal parameters
The table below lists all formal parameters of the AUXFU function:
Signal Type Type Value range Remark
Chan I BYTE 0 to 9 No. of NC channel -1
Example
FUNCTION FC 12: VOID
//Event control of auxiliary functions
VAR_INPUT
Chan: BYTE ; //Parameter is supplied by basic program
END_VAR
VAR_TEMP
ChanDB: INT ;
END_VAR
BEGIN
L Chan;
//Channel index no., (0,1,2,..)
+ 21;
//Channel DB offset
T ChanDB;
//Save channel DB no.
TO DB[ChanDB];
//Channel DB is opened indirectly
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