9-4
9.2 Handling BCD Data
9.2.1 BCD Data
BCD is an acronym for binary-coded decimal, and means that each digit of a decimal number is
expressed as a binary number.
<Example> Expressing a decimal number in BCD:
9.2.2 Handling BCD Data in the PLC
• When inputting data from a digital switch to the PLC or outputting data to a 7-segment display (with a
decoder), the data must be in BCD form. In this case, use a data conversion instruction as shown in the
examples at below.
• BCD arithmetic instructions (F40 to F58) also exist which allow direct operation on BCD data, however,
it is normally most convenient to use BIN operation instructions (F20 to F38) as operation in the PLC
takes place in binary.
Input from a digital switch
Use the BCD-to-BIN conversion instruction F81.
Output to a 7-segment display (with decoder)
Use the BIN-to-BCD conversion instruction F80.
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