Appendix A: - IEC Operators and additional norm extending functions
ST erg_byte
ROR
Bitwise rotation of an operand to the right: erg = ROR (in, n)
erg, in and n should be of the type BYTE, WORD or DWORD. in will be shifted one bit position to the right n times while the bit that is furthest to the left will be reinserted from the left.
See in the following example in hexadecimal notation that you get different results for erg_byte and erg_word depending on the data type of the input variable (BYTE or WORD), although the values of the input variables in_byte and in_word are the same.
Example in ST:
PROGRAM ror_st
VAR
in_byte : BYTE:=16#45;
in_word : WORD:=16#45; erg_byte : BYTE; erg_word : WORD;
n: BYTE :=2;
END_VAR
erg_byte:=ROR(in_byte,n); (* Result is 16#51 *) erg_word:=ROR(in_word;n); (* Result is16#4011 *)
Example in FBD:
Example in IL:
LD 16#45
ROR 2
ST erg_byte
10.4Selection Operators
All selection operations can also be performed with variables. For purposes of clarity we will limit our examples to the following which use constants as operators.
SEL
Binary Selection.
OUT := SEL(G, IN0, IN1) means:
OUT := IN0 if G=FALSE;
OUT := IN1 if G=TRUE.
IN0, IN1 and OUT can be any type of variable, G must be BOOL. The result of the selection is IN0 if G is FALSE, IN1 if G is TRUE.
Example in IL: |
|
||
LD |
TRUE |
|
|
SEL |
3,4 |
(* IN0 = 3, IN1 =4 *) |
|
ST |
Var1 |
(* Result is 4 |
*) |
LD |
FALSE |
|
|
SEL |
3,4 |
|
|
ST |
Var1 |
(* Result is 3 |
*) |
Example in ST:
Var1:=SEL(TRUE,3,4); (* Result is 4 *)
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Appendix A: - IEC Operators and additional norm extending functions
Example in FBD:
Note: Note that an expression occurring ahead of IN1 or IN2 will not be processed if IN0 is TRUE.
MAX
Maximum function. Returns the greater of the two values.
OUT := MAX(IN0, IN1)
IN0, IN1 and OUT can be any type of variable.
Example in IL:
LD 90
MAX 30
MAY 40
MAX 77
ST Var1 (* Result is 90 *)
Example in ST:
Var1:=MAX(30,40); (* Result is 40 *)
Var1:=MAX(40,MAX(90,30)); (* Result is 90 *)
Example in FBD:
MIN
Minimum function. Returns the lesser of the two values.
OUT := MIN(IN0, IN1)
IN0, IN1 and OUT can be any type of variable.
Example in IL:
LD 90
MIN 30
MIN 40
MIN 77
ST Var1 (* Result is 30 *)
Example in ST:
Var1:=MIN(90,30); (* Result is 30 *);
Var1:=MIN(MIN(90,30),40); (* Result is 30 *);
Example in FBD:
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Appendix A: - IEC Operators and additional norm extending functions
LIMIT
Limiting
OUT := LIMIT(Min, IN, Max) means:
OUT := MIN (MAX (IN, Min), Max)
Max is the upper and Min the lower limit for the result. Should the value IN exceed the upper limit Max, LIMIT will return Max. Should IN fall below Min, the result will be Min.
IN and OUT can be any type of variable.
Example in IL:
LD 90
LIMIT 30,80
ST Var1 (* Result is 80 *)
Example in ST:
Var1:=LIMIT(30,90,80); (* Result is 80 *);
MUX
Multiplexer
OUT := MUX(K, IN0,...,INn) means:
OUT := INK.
IN0, ...,INn and OUT can be any type of variable. K must be BYTE, WORD, DWORD, SINT, USINT, INT, UINT, DINT or UDINT. MUX selects the Kth value from among a group of values.
Example in IL:
LD 0
MUX 30,40,50,60,70,80
ST Var1 (* Result is 30 *)
Example in ST:
Var1:=MUX(0,30,40,50,60,70,80); (* Result is 30 *);
Please note: An expression occurring ahead of an input other than INK will not be processed to save run time ! Only in simulation mode all expressions will be executed.
10.5Comparison Operators...
GT
Greater than
A Boolean operator which returns the value TRUE when the value of the first operand is greater than that of the second. The operands can be BOOL, BYTE, WORD, DWORD, SINT, USINT, INT, UINT, DINT, UDINT, REAL, LREAL, TIME, DATE, TIME_OF_DAY, DATE_AND_TIME and STRING.
Example in IL:
LD 20
GT 30
ST Var1 (* Result is FALSE *)
Example in ST:
VAR1 := 20 > 30 > 40 > 50 > 60 > 70;
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Appendix A: - IEC Operators and additional norm extending functions
Example in FBD:
LT
Less than
A Boolean operator that returns the value TRUE when the value of the first operand is less than that of the second. The operands can be BOOL, BYTE, WORD, DWORD, SINT, USINT, INT, UINT, DINT, UDINT, REAL, LREAL, TIME, DATE, TIME_OF_DAY, DATE_AND_TIME and STRING.
Example in IL:
LD 20
LT 30
ST Var1 (* Result is TRUE *)
Example in ST:
VAR1 := 20 < 30;
Example in FBD:
LE
Less than or equal to
A Boolean operator that returns the value TRUE when the value of the first operand is less than or equal to that of the second. The operands can be BOOL, BYTE, WORD, DWORD, SINT, USINT, INT, UINT, DINT, UDINT, REAL, LREAL, TIME, DATE, TIME_OF_DAY, DATE_AND_TIME and STRING.
Example in IL:
LD 20
LE 30
ST Var1 (* Result is TRUE *)
Example in ST:
VAR1 := 20 <= 30;
Example in FBD:
GE
Greater than or equal to
A Boolean operator that returns the value TRUE when the value of the first operand is greater than or equal to that of the second. The operands can be BOOL, BYTE, WORD, DWORD, SINT, USINT, INT, UINT, DINT, UDINT, REAL, LREAL, TIME, DATE, TIME_OF_DAY, DATE_AND_TIME and STRING.
Example in IL:
LD 60
GE 40
ST Var1 (* Result is TRUE *)
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Appendix A: - IEC Operators and additional norm extending functions
Example in ST:
VAR1 := 60 >= 40;
Example in FBD:
EQ
Equal to
A Boolean operator that returns the value TRUE when the operands are equal. The operands can be BOOL, BYTE, WORD, DWORD, SINT, USINT, INT, UINT, DINT, UDINT, REAL, LREAL, TIME, DATE, TIME_OF_DAY, DATE_AND_TIME and STRING.
Example in IL:
LD 40
EQ 40
ST Var1 (* Result is TRUE *)
Example in ST:
VAR1 := 40 = 40;
Example in FBD:
NE
Not equal to
A Boolean operator that returns that value TRUE when the operands are not equal. The operands can be BOOL, BYTE, WORD, DWORD, SINT, USINT, INT, UINT, DINT, UDINT, REAL, LREAL, TIME, DATE, TIME_OF_DAY, DATE_AND_TIME and STRING.
Example in IL:
LD 40
NE 40
ST Var1 (* Result is FALSE *)
Example in ST:
VAR1 := 40 <> 40;
Example in FBD:
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