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Data Type Size & Range Calculator

Output bit size, byte size, and min/max limits for standard PLC data types.

Configuration

Type Limits & Specs

Size (Bits) 16
Size (Bytes) 2
Minimum Value -32,768
Maximum Value 32,767
Value is Valid
info
Disclaimer of Liability: This calculator is provided for educational and estimation purposes only. By using this tool, you agree to discharge AutomationView of any liability for direct, indirect, or consequential damages resulting from its use. It is your strict responsibility to independently verify all calculations, validate the results against official manufacturer documentation, and ensure compliance with all applicable safety and engineering standards before implementing any parameters in a production environment.

Understanding PLC Data Types

In PLC programming and industrial automation, selecting the correct data type is critical. Data types dictate how memory is allocated within the controller and determine how the raw bits are mathematically interpreted—whether as a signed integer, a floating-point decimal, or a simple collection of boolean flags.

Standard Data Type Sizes and Ranges

The IEC 61131-3 standard defines several core data types used across modern automation platforms (like Siemens, Allen-Bradley, and Beckhoff). Knowing their exact size and range prevents overflow errors and ensures accurate math.

  • INT (Integer): A 16-bit signed value. It consumes 2 bytes of memory and has a range of -32,768 to 32,767. It is standard for simple counters and scaled analog inputs.
  • DINT (Double Integer): A 32-bit signed value. Consuming 4 bytes, its massive range (-2.14 billion to +2.14 billion) makes it the default integer type for modern 32-bit PLC processors like ControlLogix.
  • REAL (Floating Point): A 32-bit IEEE-754 format consuming 4 bytes. It allows for decimals and is essential for precise engineering units like temperature, pressure, and PID loop variables.
  • WORD: A 16-bit unsigned string of bits. While it occupies the same memory as an INT, it is interpreted as a raw bit pattern (0 to 65,535) rather than a mathematical number. It is typically used for status flags or hexadecimal representations.

Common Pitfalls in Data Type Selection

A frequent mistake in PLC programming is using floating-point (REAL) numbers for exact equality comparisons. Because floating-point math can introduce microscopic rounding errors, comparing two REALs using an equals (=) operator may fail. Always use a small tolerance or “deadband” when comparing floats.

Furthermore, when transmitting data over industrial networks like Modbus or EtherNet/IP, ensure both the master and slave devices agree on the data type. Sending a 32-bit DINT to a system expecting two 16-bit INTs without proper handling will result in corrupted, unreadable data.