Glossary · Automation fundamentals, platforms and components
Hexadecimal
Also known as: Hex, Base 16
German: Hexadezimal
In computing, hexadecimal is the base-16 number system, using the digits 0–9 and A–F. One hexadecimal digit represents four bits, so it is used as a compact notation for binary values, addresses and status words.
- Automation components
In one sentence
Hexadecimal is the base-16 number system (0–9, A–F); one digit represents four bits, so it is used for addresses and status words.
Example
A drive reports fault code 16#2310; the manual lists this hexadecimal value as overcurrent.
How it applies
- Engineering: IEC 61131-3 writes hexadecimal literals with the prefix 16#, for example 16#FF. Other notations are 0xFF (C-like languages) and FFh.
- Maintenance: Error codes, bit masks and addresses are often shown in hexadecimal; technicians need to convert them to bits to read status words.
- Documentation: State the notation (prefix) and whether values are hexadecimal or decimal, and use one convention throughout. For status words, a table of bits and their meaning is more useful than a hexadecimal value alone.
Hexadecimal vs. BCD
Binary-coded decimal stores each decimal digit in four bits, so 16#25 in BCD means decimal 25, not 37. Older devices and displays use BCD, which is a frequent source of misinterpretation.