Would it be possible to log the ac frequency using the emonTx?

[Robert.Wall]

Certainly.

EmonLibCM makes it available, it simply isn’t normally sent with the rest of the data. Look at the documentation for emonLibCM:

EmonLibCM - Version 2.2.2

EmonLibCM is a Continuous Monitoring alternative to EmonLib. Whereas emonLib repeats, every 5 or 10 s, a sequence of voltage and current measurements in each of the input channels for a short period, normally 200 ms, and then reports the measurements back to the sketch for onwards transmission to (for example) emonCMS; emonLibCM continuously measures in the background the voltage and all the current input channels in turn, calculates a true average quantity for each and then informs the sketch t…