RSLogix 5000 Data Types Explained with Examples

Published on Aug 05, 2025 | Category: Basic

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RSLogix 5000 uses various data types to handle different types of input, output, memory, and processing operations within the PLC. These data types define the kind of data a tag can store — whether it's a binary value, an integer, or a floating-point number. Understanding each data type is critical for efficient and error-free PLC programming.

In this article, we explain every data type used in RSLogix 5000 such as BOOL, SINT, INT, DINT, LINT, REAL, and TIME-related types. Each data type is discussed with its size, range, use case, and examples. A must-read guide for every Rockwell PLC programmer.

What is Data Type in PLC?

In PLC programming, a data type defines the kind of data a variable or tag can store. It specifies the size, format, and nature of the information used in logic operations and data handling.

For example, a BOOL data type stores only two values (0 or 1), an INT stores 16-bit signed integers, and a REAL stores floating-point numbers with decimal values. Choosing the correct data type is essential for memory efficiency, accuracy, and proper operation of the PLC program.

RSLogix 5000, used with Allen-Bradley ControlLogix and CompactLogix PLCs, supports a wide range of standard and advanced data types, including integers, floating points, time types, and user-defined types.

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What is BOOL Data Type in RSLogix 5000?

The BOOL (Boolean) data type in RSLogix 5000 is used to represent binary values — either 1 (TRUE) or 0 (FALSE). It is the simplest and most commonly used data type in PLC programming, ideal for on/off, open/closed, or high/low type of logic conditions.

Each BOOL value occupies just 1 bit of memory and is often used to control actuators, read sensor states, or execute conditional logic. For example, you might use a BOOL to determine if a motor should run (Motor_Run = TRUE) or if a valve is open (Valve_Open = FALSE).

Common Uses of BOOL Data Type

Start/Stop Pushbuttons
Limit Switches
Motor Run Status
Alarm and Fault Flags
Interlocks and Safety Conditions

bool data type example in rslogix 5000 ,This ladder program uses BOOL (Boolean) type tags to control a motor with ON/OFF logic.

Start_PB (BOOL): When TRUE (pressed), it starts the sequence.
Stop_PB (BOOL): When TRUE (pressed), it stops the sequence.
hold_sts (BOOL): Latches the output. Remains TRUE after Start_PB is released.
Motor_Run (BOOL): Turns TRUE when hold_sts is TRUE — represents motor ON.

The logic uses BOOL values (TRUE/FALSE) to control each step in the motor start/stop process.

Numerical Data Types in RSLogix 5000

RSLogix 5000 supports various numerical data types to handle signed and unsigned integer values of different sizes. Each type is optimized for specific memory usage and application needs.

1. SINT – Short Integer (8-bit)

Range: -128 to 127
Usage: Suitable for small counters, flags, and byte-level operations.

2. INT – Integer (16-bit)

Range: -32,768 to 32,767
Usage: Ideal for basic arithmetic or medium-range counters.

3. DINT – Double Integer (32-bit)

Range: -2,147,483,648 to 2,147,483,647
Usage: Most commonly used data type in RSLogix 5000 for math, timers, and counters.

4. LINT – Long Integer (64-bit)

Range:0 to 32535129599999999
Usage: Used where very large numbers are required, like high-resolution timestamps or accumulators.

5. USINT – Unsigned Short Integer (8-bit)

Range: 0 to 255
Usage: For byte values that never go negative, e.g., status codes or digital ranges.

6. UINT – Unsigned Integer (16-bit)

Range: 0 to 65,535
Usage: For medium-range values where negative numbers are not needed.

7. UDINT – Unsigned Double Integer (32-bit)

Range: 0 to 4,294,967,295
Usage: Used in counters, timestamps, and serial data where only positive values are allowed.

What is REAL Data Type in RSLogix 5000?

The REAL data type in RSLogix 5000 is a 32-bit floating-point number based on the IEEE 754 standard. It is used to store decimal numbers with fractional values — both positive and negative.

Range of REAL Data Type:

Negative range: -3.402823E38 to -1.1754944E-38
Zero: 0
Positive range: 1.1754944E-38 to 3.402823E38

Common Uses:

Analog signal scaling (e.g., 4-20 mA to 0.0–100.0)
Storing temperature, flow, and pressure readings
Performing PID control and mathematical operations

Example:

If a sensor reads 18.56°C, the value is stored in a REAL tag like Temp_Value.

// Example
REAL Temp_Value = 18.56;