Do not look to Rockwell ST as a resource for learning ST for Codesys. Rockwell ST is so far removed (in a bad way) from where everyone else is that it would be mostly pointless.
The best thing to do would be to learn/practice any text based language since they all use the same basic constructs (IF, FOR, WHILE, CASE/SWITCH, etc) to familiarize yourself with text based programming. ANSI C is actually pretty close to ST, so it is a good choice with loads of learning resources. I only recommend that because there is a noticeable lack of learning resources for ST directly.
Here is a list of fairly standard keywords:
ACCESS
Defines dynamic access. See also "Dynamic variables".
BIT_CLR
A = BIT_CLR(IN, POS)
A contains the value IN after the bit at position POS is deleted. However, the IN operand remains unchanged.
BIT_SET
A = BIT_SET(IN, POS)
A contains the value IN after the bit at position POS is set. However, the IN operand remains unchanged.
BIT_TST
Determines the value of a bit: A := BIT_TST(IN, POS)
A contains the value of the bit at position POS of operand IN.
BY See FOR statement.
CASE See CASE statement.
DO See WHILE statement.
EDGE
Detects positive and negative edges.
A frequent application error is skipping an expression with EDGE (i.e. with an IF statement).
EDGENEG
Detects negative edges.
A frequent application error is skipping an expression with EDGENEG (i.e. with an IF statement).
EDGEPOS
Detects positive edges.
A frequent application error is skipping an expression with EDGEPOS (i.e. with an IF statement).
ELSE See IF statement.
ELSIF See IF statement.
END_CASE See CASE statement.
END_FOR See FOR statement.
END_IF See IF statement.
END_REPEAT See REPEAT statement.
END_WHILE See WHILE statement.
EXIT See EXIT statement.
FOR See FOR statement.
IF See IF statement.
OF See CASE statement.
REPEAT See REPEAT statement.
RETURN See RETURN statement.
THEN See IF statement.
TO See FOR statement.
UNTIL See REPEAT statement.
WHILE See WHILE statement.
Operators:
ABS
Returns the absolute value of a number. ABS(-2) returns 2.
ACOS
Returns the arc cosine (inverse function of cosine) of a number.
adr
Returns a variable's address.
ADRINST Can only be called from within a function block and returns the instance address of the current function block
AND
Logical AND operation by bit.
ASIN
Returns the arc sine of a number (inverse function of sine).
ASR
Mathematically shifts an operand to the right: A := ASR (IN, N);
Shifts IN to the right by N bits and fills in the left with the sign bit.
ATAN
Returns the arc tangent of a number (inverse function of tangent).
COS
Returns the cosine of a number.
EXP
Exponential function: A := EXP (IN).
EXPT
One operand raised to the power of another operand: A := EXPT (IN1, IN2).
LIMIT
Limitation: A := LIMIT (MIN, IN, MAX);
MIN is the lower limit, MAX is the upper limit for the result. If IN is less than MIN, then the MIN result is returned. If IN is greater than MAX, then the MAX result is returned. Otherwise, the IN result is returned.
LN
Returns the natural logarithm of a number.
LOG
Returns the base-10 logarithm of a number.
MAX
Returns the largest value as the result.
MIN
Returns the smallest value as the result.
MOD Modulo division of a USINT, SINT, INT, UINT, UDINT, DINT type variable by another variable of one of these types.
MOVE The contents of the input variable are copied to the output variable. The := symbol is used as the assignment operator.
"A := B;" is the same as "A := MOVE (B);"
MUX
Selection: A = MUX (CHOICE, IN1, IN2, ... INX);
CHOICE specifies which of the operators IN1, IN2, ... INX is returned as a result.
NOT Negation of a bit operand by bit.
OR
Logical OR operation by bit.
ROL
Left bit rotation of an operand: A := ROL (IN, N);
IN is shifted N times to the left one bit position at a time, the far left bit being pushed in again from the right.
ROR
Right bit rotation of an operand: A := ROR (IN, N);
IN is shifted N times to the right one bit position at a time, the far right bit being pushed in again from the left.
SEL
Binary selection: A := SEL (WAHL, IN1, IN2)
CHOICE must be of type BOOL. If CHOICE is FALSE, then IN1 is returned. Otherwise, IN2 is returned.
SHL
Left bit shift of an operand: A := SHL (IN, N);
IN is shifted left by N bits and filled from the right with zeros.
SHR
Right bit shift of an operand: A := SHR (IN, N);
IN is shifted right by N bits and filled from the left with zeros.
SIN
Returns the sine of a number.
sizeof
If a variable is specified as the operand, then SIZEOF returns the number of bytes needed by the specified variable.
If a type name is specified as the operand, then SIZEOF returns the number of bytes needed by the specified type.
SQRT
Returns the square root of a number.
TAN
Returns the tangent of a number.
TRUNC
Returns the integer part of a number.
XOR
Logical EXCLUSIVE OR operation by bit.
Expressions:
Pentheses (Expression)
Function call FunctionName(parameter list);
Negate -
NOT
Raise to the power **
Multiply *
Divide /
Modulo MOD
Add +
Subtract -
Comparisons <,>,<=,>=
Equal to =
Not equal to <>
Bitwise AND operation AND
Bitwise EXCLUSIVE OR operation XOR
Bitwise OR operation OR
EDIT: The three lists are copy/past from Automation Studio help, but should be more or less the same for whatever flavor of Codesys you are using.
