What we are trying to say is you need to RTFM and learn how the data is stored and scaled in your meter.
Once you know how the data is stored and how to convert it to a "real value" we can probably help you with the code.
We don't know anything about your device so there is really nothing we can do besides give you very general advice like:
Most times obtaining accurate measurements through MODBUS you have to combine several registers and maybe multiply by a scaling factor to get the actual value.
But what registers, how many, and what scaling varies from device to device so there is no one right answer.
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=== Engineer Ambiguously ===
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