Modbus Communication between EATON Power Meter and Accuenergy Data Acquisition Server

The Eaton meter uses an absolute starting address of 40000 decimal with all mapped values indexed from the starting 40000 value (which is not noted on the published map).

The map tells us that "watts, 3-Ph" register is at zero-based address 0x0383, (one-based 900 decimal).

The relative indexed register is apparently calculated as one-based 40000 decimal + 900 decimal = 40900 decimal = 0x9FC4, but the master needs a zero-based hex value so the zero-based address is one less, or 0x9FC3

The critical information about the 40000 decimal absolute starting address is missing from the Modbus map. Not only is it confusing, but it forces implementers to calculate every hex indexed offset, instead of using the hex value on the table.

The absolute starting address of 40000 is really confusing when it is omitted from the published map. The equivalent 6 digit addressing should be represented on the map as (4)40900, not 900; or 0x9FC3 instead of 0x0383.

It is reprehensible for Eaton to not include the 40000 offset without noting such on the Modbus map.

Eaton qualifies for nomination to the Modbus Hall of Shame.