Lenze PLC Designer PLC Designer (R2-x) - Manual (Page 650)

L-force | PLC Designer
PLC Designer Libraries
648 DMS 3.2 EN 02/2011 TD29

SEMA
Provided by standard.lib.
A Software Semaphore (Interruptible)
BUSY = SEMA(CLAIM, RELEASE) means:
BUSY := X;
IF CLAIM THEN X:=TRUE;
ELSE IF RELEASE THEN BUSY := FALSE; X:= FALSE;
END_IF
X is an internal BOOL variable that is FALSE when it is initialized.
The input variables CLAIM and RELEASE as well as the output variable BUSY are type
BOOL.
If BUSY is TRUE when SEMA is called up, this means that a value has already been
assigned to SEMA (SEMA was called up with CLAIM = TRUE). If BUSY is FALSE, SEMA
has not yet been called up or it has been released (called up with RELEASE = TRUE).
Declaration example:
SEMAInst : SEMA ;
Example in IL:
CAL SEMAInst(CLAIM:=VarBOOL1,RELEASE:=VarBOOL2)
LD SEMAInst.BUSY
ST VarBOOL3
Example in FBD:
Example in ST:
SEMAInst(CLAIM:= VarBOOL1 , RELEASE:=VarBOOL2 );
VarBOOL3 := SEMAInst.BUSY;