Signals and PLC · Glossary
What is Binary Coded Decimal?
Symbol: BCD4 bits per digitSignals and PLC
Binary coded decimal stores each decimal digit as its own 4 bit binary group, used by thumbwheels, displays and some timers.
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Binary Coded Decimal Explained
The number 59 is stored as 0101 1001. BCD is easy to show on displays, but uses more bits than plain binary.
Older PLC timers and some device registers use BCD, so values must be converted before arithmetic.
Binary Coded Decimal Formula
Value = Σ digiti × 10i
| digit | each 4 bit group, 0 to 9 |
Example: 0001 0010 0101 = 125 decimal.
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Calculators for Binary Coded Decimal
Frequently Asked Questions
What is Binary Coded Decimal?
Binary coded decimal stores each decimal digit as its own 4 bit binary group, used by thumbwheels, displays and some timers.
Is 1010 valid BCD?
No, each group must be 0 to 9.
Why do I see 4660 instead of 1234?
The register holds BCD 1234 (0x1234) but was read as binary.
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