Which statement best describes ASCII within PLC contexts?

• A. It is a text encoding standard
• B. It is a binary data format
• C. It is a graphic image format
• D. It is a voltage reference standard

Answer: (A)

ASCII is a text encoding standard used to represent human-readable characters with numeric codes in digital systems, including PLCs. In PLC communications and data exchange, characters and strings are often transmitted by encoding each character as its ASCII value (for example, 'A' corresponds to 65). This standard underpins how text is sent over serial links or displayed in HMIs, and some protocols (like Modbus ASCII) rely on these ASCII representations. It’s not a binary data format in itself, even though the encoded characters are stored as binary numbers, and it isn’t a graphic image format or a voltage reference standard.