Lenze PLC Designer PLC Designer (R2-x) - Manual (Page 654)

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

Declaration example:
CTUInst : CTU ;
Example in IL:
CAL CTUInst(CU := VarBOOL1, RESET := VarBOOL2, PV :=
VarINT1)
LD CTUInst.Q
ST VarBOOL3
LD CTUInst.CV
ST VarINT2
Example in FBD:
Example in ST:
CTUInst(CU:= VarBOOL1, RESET:=VarBOOL2 , PV:= VarINT1);
VarBOOL3 := CTUInst.Q ;
VarINT2 := CTUInst.CV;
CTD
Provided by standard.lib.
Function Block Decrementer:
The input variables CD and LOAD as well as the output variable Q are type BOOL, the
input variable PV and the output variable CV are type WORD.
When LOAD_ is TRUE, the counter variable CV will be initialized with the upper limit
PV. If CD has a rising edge from FALSE to TRUE, CV will be lowered by 1 provided CV is
greater than 0 (i.e., it doesn't cause the value to fall below 0).
Q returns TRUE when CVis equal 0.