What is a descriptor in HART, and how is it used?

• A. A parameter's numerical value.
• B. A human-readable text string describing a variable or parameter; documents what a variable represents.
• C. A binary flag indicating device status.
• D. A cryptographic key used for security.

Answer: (B)

In HART, a descriptor is a human-readable text string that names and explains a variable or parameter, documenting what the data represents. This descriptor travels with the numeric value so field communicators and asset-management software can show meaningful labels like "Flow rate," "Process temperature," or "Valve position" instead of cryptic codes. It helps technicians quickly understand what a measurement or setting refers to, making configuration, calibration, and troubleshooting much more straightforward. It’s not a numerical value, not a binary flag, and not a cryptographic key—the descriptor’s role is to provide clear, human-friendly context for the data.