Nexto XF #70 – Accessing Variable Bits

This tutorial will show how to access individual bits of analog variables directly in MasterTool X, allowing you to manipulate specific parts of an integer or Word-type value.

Components

Equipment: 1 computer/laptop.

Software:  MasterTool X

Tutorial Sections

1. ARCHITECTURE
2. DEVELOPMENT

1.ARCHITECTURE

A computer/laptop will be required to use MasterTool X.

Figure 1. Computer running MasterTool X

2.DEVELOPMENT

Accessing variable bits is widely used in automation applications where the goal is to optimize memory use and control multiple states within a single variable, commonly found in communication systems, signaling, and internal process control.

Concept

Variables of the type:

• INT
• WORD

are stored internally in binary form, meaning they consist of bits that can be accessed individually.

Access method

To access a specific bit of a variable, use the following syntax:

variable_name.bit

Examples:

• temperatura.0 → accesses bit 0
• temperatura.5 → accesses bit 5

Application in Logic

Bits can be used directly in Ladder logic as boolean signals.

Practical example:

• Normally open contact: temperatura.0
• Coil: temperatura.5

Figure 2. Accessing bits of an analog variable

Example operation

By actuating bit 0 through the contact and bit 5 through the coil, both become TRUE within the variable.

Value interpretation

Each bit represents a power of 2:

• Bit 0 → 2⁰ = 1
• Bit 5 → 2⁵ = 32

If both are active:

1 + 32 = 33

That is, when viewing the complete variable:

temperatura = 33

Figure 3. Manipulating bits of an analog variable

Applications in automation

• Control of multiple states in a single variable
• Communication with devices
• Use of registers
• Memory optimization
• Control flags

Important notes

• More common in INT and WORD variables
• Each bit has a specific binary weight
• Avoid overwriting bits without control
• Allows detailed manipulation of the variable