emonTx v3.4 rms voltage in USA, and raw Tx data units?

Almost, I don’t think you need the “-1*” as that would make it a positive number.

[EDIT] although I would have probably expressed it as (pseudo code)

x= (a + (b*256)) 
if x > (2^16/2)
    x = (x - (2^16)) 
return x