etisserant@0: (* Following taken directly from the IEC 61131.3 draft standard *)
etisserant@0: 
etisserant@0: (*
etisserant@0:  * An IEC 61131-3 IL and ST compiler.
etisserant@0:  *
etisserant@0:  * Based on the
etisserant@0:  * FINAL DRAFT - IEC 61131-3, 2nd Ed. (2001-12-10)
etisserant@0:  *
etisserant@0:  *)
etisserant@0: 
etisserant@0: 
etisserant@0: (*
etisserant@0:  * This is part of the library conatining the functions
etisserant@0:  * and function blocks defined in the standard.
etisserant@0:  *
etisserant@0:  * Counter function blocks
etisserant@0:  * -----------------------
etisserant@0:  *)
etisserant@0: 
etisserant@0: 
etisserant@0: FUNCTION_BLOCK CTU
etisserant@0:   VAR_INPUT
etisserant@0:     CU : BOOL;
etisserant@0:     R : BOOL;
etisserant@0:     PV : INT;
etisserant@0:   END_VAR
etisserant@0:   VAR_OUTPUT
etisserant@0:     Q : BOOL;
etisserant@0:     CV : INT;
etisserant@0:   END_VAR
etisserant@0:   VAR RETAIN
etisserant@0:     PVmax : INT;
etisserant@0:   END_VAR
etisserant@0:   IF R THEN CV := 0 ;
etisserant@0:   ELSIF CU AND (CV < PVmax)
etisserant@0:        THEN CV := CV+1;
etisserant@0:   END_IF ;
etisserant@0:   Q := (CV >= PV) ;
etisserant@0: END_FUNCTION_BLOCK
etisserant@0: 
etisserant@0: 
etisserant@0: FUNCTION_BLOCK CTD
etisserant@0:   VAR_INPUT
etisserant@0:     CD : BOOL;
etisserant@0:     LD : BOOL;
etisserant@0:     PV : INT;
etisserant@0:   END_VAR
etisserant@0:   VAR_OUTPUT
etisserant@0:     Q : BOOL;
etisserant@0:     CV : INT;
etisserant@0:   END_VAR
etisserant@0:   VAR RETAIN
etisserant@0:     PVmin : INT;
etisserant@0:   END_VAR
etisserant@0:   IF LD THEN CV := PV ;
etisserant@0:   ELSIF CD AND (CV > PVmin)
etisserant@0:       THEN CV := CV-1;
etisserant@0:   END_IF ;
etisserant@0:   Q := (CV <= 0) ;
etisserant@0: END_FUNCTION_BLOCK
etisserant@0: 
etisserant@0: 
etisserant@0: FUNCTION_BLOCK CTUD
etisserant@0:   VAR_INPUT
etisserant@0:     CU : BOOL;
etisserant@0:     CD : BOOL;
etisserant@0:     R  : BOOL;
etisserant@0:     LD : BOOL;
etisserant@0:     PV : INT;
etisserant@0:   END_VAR
etisserant@0:   VAR_OUTPUT
etisserant@0:     QU : BOOL;
etisserant@0:     QD : BOOL;
etisserant@0:     CV : INT;
etisserant@0:   END_VAR
etisserant@0:   VAR RETAIN
etisserant@0:     PVmax : INT;
etisserant@0:     PVmin : INT;
etisserant@0:   END_VAR
etisserant@0:   IF R THEN CV := 0 ;
etisserant@0:   ELSIF LD THEN CV := PV ;
etisserant@0:   ELSE
etisserant@0:     IF NOT (CU AND CD) THEN
etisserant@0:       IF CU AND (CV < PVmax)
etisserant@0:       THEN CV := CV+1;
etisserant@0:       ELSIF CD AND (CV > PVmin)
etisserant@0:       THEN CV := CV-1;
etisserant@0:       END_IF;
etisserant@0:     END_IF;
etisserant@0:   END_IF ;
etisserant@0:   QU := (CV >= PV) ;
etisserant@0:   QD := (CV <= 0) ;
etisserant@0: END_FUNCTION_BLOCK
etisserant@0: