How are device diagnostics communicated in HART?

How are device diagnostics communicated in HART?

• A. Analog signals only
• B. Digital variables via read commands or burst data
• C. Only during manufacturing
• D. Diagnostics are not supported

Answer: (B)

In HART, device diagnostics are carried as digital data on the digital portion of the protocol, not as changes to the analog current. The master can read these diagnostics by issuing read commands to pull digital variables, which describe health, status, faults, calibration, and other diagnostic information. The device can also send diagnostics automatically in burst mode, periodically broadcasting digital data without a poll. This digital channel runs alongside the analog 4–20 mA signal, so you get rich diagnostic information without interrupting the process. So diagnostics are communicated as digital variables via read commands or burst data.

In HART, device diagnostics are carried as digital data on the digital portion of the protocol, not as changes to the analog current. The master can read these diagnostics by issuing read commands to pull digital variables, which describe health, status, faults, calibration, and other diagnostic information. The device can also send diagnostics automatically in burst mode, periodically broadcasting digital data without a poll. This digital channel runs alongside the analog 4–20 mA signal, so you get rich diagnostic information without interrupting the process. So diagnostics are communicated as digital variables via read commands or burst data.