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Basic Data Types

BOOL Type​

The BOOL data type represents a binary value: 1 (true) or 0 (false). It’s commonly used for conditions, switches, and digital I/O.

Examples:​

IF Start_Button THEN
    Motor_Running := 1;
END_IF;

Use BOOL for:

  • Inputs like push buttons or limit switches

  • Outputs like motors, lights, alarms

  • Internal flags and conditions

Integer Types​

DINT​

  • 32-bit signed integer: range from -2,147,483,648 to 2,147,483,647

Examples:​

Count := Count + 1;
Speed_Setpoint := 100;

Real Numbers​

REAL​

  • 32-bit floating-point number

  • Supports decimal values like 23.7, -5.25, etc.

  • Used for math, measurement, and analog signals

Examples:​

Temperature := 21.5;
Flow_Rate := Flow_Rate + 0.1;

Use REAL when:

  • Working with temperature, pressure, or flow sensors

  • Performing calculations that require fractions

Note: Use := to assign decimal values, and avoid mixing DINT and REAL types without proper conversion if needed.

Type Examples​

Here's a few examples of Data Types in Structured Text:

VariableTypeExplanation
Motor_RunningBOOLIndicates whether the motor is running (on/off).
CountDINTStores a running total as a 32-bit integer.
TemperatureREALHolds a temperature value with decimal precision.