Unitless conversion

[TrystanLea]

Approach

• Unitless code included in the _process_rx method in emonhub_interfacer.py
• Unitless conversion happens after datacode decoding and before scale application in _process_rx
• This allows unitless conversion to be used by all interfacers e.g tested with JeeInterfacer and SocketInterfacer.
• Vcal and Ical calibration factors can be applied as part of existing scales mechanism

Part 1 conversion code, hard coded testing:
emon-pi...486ca72

Part 2 conversion code, unitless structure specified in emonhub.conf:
emon-pi...115c01a

EmonHub.conf example

[[10]]
    nodename = emontx1
    [[[rx]]]
       names = power1, power2, power3, power4, vrms
       datacode = h
       phase_shift = 0.0
       unitless = rp,rp,rp,rp,v
       scales = 24131.42,24131.42,24131.42,24131.42,266.41

Power input scale factor is product of vcal and ical:

vcal = 266.41
ical = 90.91 (2000 turns / 22R burden resistor)
vcal x ical = 24131.42