Commission a Modbus energy meter without guessing the map

Prove the physical and protocol route

For RTU, record the exact serial device, baud rate, parity, stop bits, Unit ID, timeout, and adapter. For TCP, prove the host, port, Unit ID, and whether a gateway is involved. Start with one documented measurement instead of scanning the complete space.

Resolve addressing and float layout independently

Translate the manual's printed 3xxxx address into a zero-based PDU offset before changing byte order. Then test ABCD, CDAB, BADC, or DCBA against a known measurement. Fixing two unknowns at once makes a plausible value easy to misread as proof.

• Keep documentation and PDU addresses side by side
• Verify the register width
• Compare against the meter display or reference instrument
• Repeat with a second value that changes predictably

• Check the captured voltage bytes →

Import a reviewed definition or build bounded sources

A reviewed device definition can provide groups, offsets, types, units, and source ranges without carrying installation-specific connection settings. Otherwise, create small contiguous FC04 sources around documented blocks and check every range boundary.

• Use the Eastron SDM630 register map →
• Inspect the Siemens PAC3200 register map →

Trend values and retain commissioning evidence

Trend phase voltages, currents, power, frequency, power factor, and energy counters at a rate the meter can sustain. Use alarms for clear boundaries, then export a report or recording that retains the route and raw context needed to reproduce a questionable value.