How does the Modbus register work and why is it in hexadecimal? (3x0000 to 3xFFFF)
Modbus registers work as a way to store and exchange data in Modbus communication, which is a popular protocol used in industrial automation and control systems. Modbus registers are typically 16-bit values, and they are indeed represented in hexadecimal format. Here's an explanation of how Modbus registers work and why hexadecimal is used:
- Data Storage: Modbus registers are used to store various types of data, such as sensor readings, control parameters, status information, and more. These registers are organized in a range from 0x0000 to 0xFFFF, which covers 65,536 possible values.
- 16-Bit Format: Each Modbus register is 16 bits (2 bytes) in length. This means that it can hold values ranging from 0 to 65,535. The 16-bit format is common in industrial control systems because it provides a good balance between precision and data size.
- Hexadecimal Representation: Hexadecimal (base-16) is used to represent Modbus registers for several reasons:
- Compactness: Hexadecimal allows for a compact representation of binary data. Each hexadecimal digit represents four binary bits, making it efficient for displaying and working with 16-bit values.
- Human Readability: Hexadecimal is more human-readable than binary or decimal for 16-bit values. It uses the digits 0-9 and the letters A-F to represent values from 0 to 15.
- Alignment: Hexadecimal values align neatly with bytes. In a Modbus register, each byte is represented by two hexadecimal digits, making it easier to work with when dealing with byte-oriented communication protocols.
- Consistency: Hexadecimal is consistent with the way data is often displayed and configured in industrial control systems and related software.
- Addressing: The "3x" in "3x0000 - 3xFFFF" refers to the Modbus function codes. In Modbus, function codes 3 and 4 are used for reading and writing registers. The "x" in "3x" signifies that these registers are in the "holding registers" category. Holding registers are used to store data that can be read and written by external devices