Electrician here, got handed the SCADA side of a sub meter because nobody else would touch it. Power meter on the main incomer, Modbus TCP, Ignition 8.1 Modbus driver. The meter manual says kW is a 32-bit float at holding registers 3054 and 3055, so I made an address HRF3054 and the tag reads 1.27e+30, or sometimes minus a few million. The meter's own display says 401 kW.
Thought it might be an off by one, so I tried 3053 and 3055 as the start and got a zero and a different piece of nonsense. The voltage registers, which the manual has as 16-bit, read right to the volt, so the connection and the unit ID are fine.
Two days on one tag and I'm at a loss. Any ideas where I'm going wrong on the float?
Which page of the manual, and does it give the two registers as high word first or low word first? Some meters print it in the notes as "float, LSW first". And post the raw values of 3054 and 3055 as two separate 16-bit reads, HR3054 and HR3055.