Lenze DDS v2.3 - Manual (Page 303)

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IEC 61131-3 Standard functions
14-11
l
DDS EN 2.3
14.4.3 SEMA
Software semaphore (interruptible)
X is an internal BOOL variable initialized with FALSE .
BUSY , CLAIM and RELEASE are of type BOOL.
•
If SEMA is called and BUSY is TRUE, SEMA has already been assigned
(SEMA was called using CLAIM = TRUE).
•
If BUSY is FALSE, SEMA has either not been called yet or been enabled
(call with RELEASE = TRUE).
BUSY = SEMA(CLAIM, RELEASE) means:
BUSY:=X;
IF CLAIM THEN X:=TRUE;
ELSIF RELEASE THEN BUSY:=FALSE; X:=FALSE;
END_IF
Examples
Declaration:
SEMAInst : SEMA;
IL FBD
CAL SEMAInst(CLAIM:=VarBOOL1, RELEASE:=VarBOOL2)
LD SEMAInst.BUSY
ST VarBOOL3
ST
SEMAInst(CLAIM:=VarBOOL1, RELEASE:=VarBOOL2);
VarBOOL3:=SEMAInst.BUSY;
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