99
6-1-3
Structure of ST and Example
Using general expressions, ST programming requires no special knowledge.
Remember the following two rules:
(1) Use a colon and an equals sign (:=) to assign a value to a variable.
(2) Statements must end with a semicolon (;).
Example
An example of the statement to calculate the distance between two points using Pythagoras'
theorem is shown below.
Just apply the formula.
■ Formula
𝐋𝐞𝐧𝐠𝐭𝐡 = �(𝐗𝟏 − 𝐗𝟎)
𝟐
+ (𝐘𝟏 − 𝐘𝟎)
𝟐
■ ST program
Length := SQRT((X1-X0)**2+(Y1-Y0)**2);
* SQRT: Square Root
6-1-4
Operators
Operator
Operation
Notation example
Priority
()
First priority
Value := (1+2)*(3+4);
// Value is 21
1
-, +
Sign
+100, -100
2
NOT
Logical NOT
Value := NOT TRUE;
// Value is FALSE
**
Exponent
Value := 2**8;
// Value is 256
3
*
Multiplication
Value := 8*100;
// Value is 800
4
/
Division
Value := 200/25;
// Value is 8
MOD
Remainder
Value := 10 MOD 6;
// Value is 4
+
Addition
Value := 200+25;
// Value is 225
5
-
Subtraction
Value := 200-25;
// Value is 175
<, >, <=, >=
Comparison
Value := 60>10;
// Value is TRUE
6
=
Matches
Value := 8=7;
// Value is FALSE
7
<>
Does not match
Value := 8<>7;
// Value is TRUE
&, AND
Logical AND
Value := 2#1001 AND 2#1100;
// Value is 2#1000
8
XOR
Logical exclusive OR
Value := 2#1001 XOR 2#1100; // Value is 2#0101
9
OR
Logical OR
Value := 2#1001 XOR 2#1100; // Value is 2#1101
10
