PLC Programming

Appendix D: CoDeSys Libraries
Example in FBD:
Example in ST:
CTUInst(CU:= VarBOOL1, RESET:=VarBOOL2 , PV:= VarINT1);
VarBOOL3 := CTUInst.Q ;
VarINT2 := CTUInst.CV;
CTD
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 INT.
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.
Declaration example:
CTDInst : CTD ;
Example in IL:
CAL
LD
ST
LD
ST
CTDInst(CD := VarBOOL1, LOAD := VarBOOL2, PV := VarINT1)
CTDInst.Q
VarBOOL3
CTDInst.CV
VarINT2
Example in FBD:
Example in ST:
CTDInst(CD:= VarBOOL1, LOAD:=VarBOOL2 , PV:= VarINT1);
VarBOOL3 := CTDInst.Q ;
VarINT2 := CTDInst.CV;
CoDeSys V2.3 10-47