ADE7858A datasheet rev.D P.45 describes below.
"during the chip power-up and DSP reset cases, it typically takes about 1.2 seconds for an FS/1000 signal to be settled"
I think that it takes some time addition to settling time after DSP RUN=1 (register 0xE228) from above description.
How long does it take for FS/1000 signal to be settlied after DSP of ADE7858A is set to RUN=1(0xE228) ?
( 1.2 seconds or settling time only ?)