Lenze PLC Designer PLC Designer (R3-1) - Manual (Page 760)

L-force | PLC Designer
General Editors
758 DMS 4.1 EN 03/2011 TD29

Assignment as expression
As extension to the IEC 61131-3 standard (ExST), »PLC Designer« allows assignments
to be used as an expression.
Examples:
int_var1 := int_var2 := int_var3 + 9; (* int_var1
real_var1 := real_var2 := int_var; (* correct assignments, real_var1 and real_var2 will get the
value of int_var *)
int_var := real_var1 := int_var; (* this will lead to an error message because of type
mismatch real-int ! *)
IF b := (i = 1) THEN
i := i + 1;
END_IF
Instructions
Instructions tell what to do with the given expressions. The following instructions can
be used in ST:
Instruction type Example
Assignment
(see also: Assignment operators) A:=B; CV := CV + 1; C:=SIN(X);
Calling a function block and
use of the FB output CMD_TMR(IN := %IX5, PT := 300);
A:=CMD_TMR.Q
RETURN RETURN;
IF D:=B*B;
IF D<0.0 THEN
C:=A;
ELSIF D=0.0 THEN
C:=B;
ELSE
C:=D;
END_IF;
CASE CASE INT1 OF
1: BOOL1 := TRUE;
2: BOOL2 := TRUE;
ELSE
BOOL1 := FALSE;
BOOL2 := FALSE;
END_CASE;