Documentation

ST language commands

The ST language commands are ending by a semicolon. The EOL character is treated in the same way as the space character.

Command Description Example
:= Assignment.
The value calculated on the right is assigned to the identifier on the left.
A:=B; C:=SIN(X); My_FB(p1:=10, p2:=20);
=> Assignment.
Value of the variable declared on the left is assigned to the identifier on the right.
FB1( out1 => my_var );
REF= Reference.
Variable on the left is filled with reference to the value on the right.
MyVar:= 100; MyRef REF= MyVar; MyRef:= 200;
IF Selection command.
If the BOOLean condition is met the associated command is executed.
IF A>10 THEN B:=1;
ELSE B:=2;
END_IF;
CASE Selection command.
Execution of a block of commands if the CASE condition is met.
CASE TW OF
1,5: DISPLAY:=OVEN_TEMP;
2: DISPLAY:=MOTOR_SPEED;
ELSE DISPLAY:=STATUS;
END_CASE;
FOR Iterative command.
A loop of block of commands with an initial value, end condition, and increment value.
FOR I:= 0 TO 10 BY 2
DO
J:=J+3;
END_FOR;
WHILE Iterative command.
A loop of block of commands with condition for exiting the loop at the beginning.
WHILE J>10 DO
J:=J+2;
END_WHILE;
REPEAT Iterative command.
A loop of block of commands with condition for exiting the loop at the end.
REPEAT
J:=J+2;
UNTIL J>10;
EXIT Exiting the loop.
Premature exiting of the command loop.
EXIT;
RETURN Return.
Leaving of the currently executed block.
RETURN;