BCD (Binary-Coded Decimal) is a digital encoding method where each decimal digit (0-9) is represented by a fixed 4-bit binary sequence. Unlike standard binary arithmetic, which converts an entire number into a single binary value, BCD handles each digit independently.
For example, the decimal number 259 is represented in BCD as follows:
- 2:
0010 - 5:
0101 - 9:
1001
Combined, the BCD value is 0010 0101 1001. In contrast, standard binary representation would express 259 as a single sequence: 100000011.
Applications in Industrial Control
Originally developed to simplify the circuitry for driving digital displays (such as 7-segment LEDs), BCD remains relevant in industrial automation. Engineers often encounter BCD formats when interfacing with Programmable Logic Controllers (PLCs), digital I/O modules, or legacy measurement instruments.
While BCD is less memory-efficient than pure binary, it offers advantages in precision for decimal arithmetic and ease of interfacing with human-readable displays. When developing control software for equipment requiring BCD input, programmers must convert standard binary integers into BCD format before transmission.