DLMS Extended Register (Class 4) Status Byte Bitmask: Reverse Flow & Tamper Detection

[sarah_jenkins]

Understanding the Status Octet in Class 4 Energy Registers

Class 4 (Extended Register) couples measurement values with a status byte and capture timestamp.

Standard Status Bitmask (DLMS Blue Book Ed. 14)

Bit 0: Invalid Data (Value calculation corrupted or sensor offline)
Bit 1: Doubtful Value (Uncertain measurement precision)
Bit 2: Measurement Value Modified (Manual adjustment or calibration)
Bit 3: Power Failure (Occurred during integration period)
Bit 4: Clock Synchronized (RTC synchronized via external time server)
Bit 5: Daylight Saving Time Active
Bit 6: Overflow (Energy register counter rollover)
Bit 7: Reverse Energy Flow Detected (Indicates possible reverse wiring/tamper)

Checking Bit 7 on Active Energy Import registers immediately detects field wiring inversion errors!

[carlos_mendez]

Bit 7 monitoring saved us during a major retrofit: we flagged 35 meters wired in reverse phase on the very first day of automated AMR collection.

[elena_rostova]

In the meter metrology core, reverse power detection triggers an internal tamper counter and logs the event to the metrological audit log (0.0.96.11.0.255).