PLC Programming

Appendix D: CoDeSys Libraries
Example in FBD:
Example in ST:
arINT1 := FIND ('SUXYSI','XY');
Please Note: String functions are not "thread safe": When using tasks, string functions may only be used in a
single task. If the same function is used in different tasks, there is a danger of overwriting.
10.16.2 Bistable Function Blocks...
SR
Making Bistable Function Blocks Dominant:
Q1 = SR (SET1, RESET) means:
Q1 = (NOT RESET AND Q1) OR SET1
The input variables SET1 and RESET as well as the output variable Q1 are type BOOL.
Declaration example:
SRInst : SR ;
Example in IL:
CAL
LD
ST
SRInst(SET1 := VarBOOL1, RESET := VarBOOL2)
SRInst.Q1
VarBOOL3
Example in FBD:
Example in ST:
SRInst(SET1:= VarBOOL1 , RESET:=VarBOOL2 );
VarBOOL3 := SRInst.Q1 ;
RS
Resetting Bistable Function Blocks
Q1 = RS (SET, RESET1) means:
Q1 = NOT RESET1 AND (Q1 OR SET)
The input variables SET and RESET1 as well as the output variable Q1 are type BOOL.
Declaration example:
RSInst : RS ;
Example in IL:
CAL
LD
RSInst(SET := VarBOOL1, RESET1 := VarBOOL2)
RSInst.Q1
CoDeSys V2.3 10-43