If you need a WattNode® meter for LonWorks® that behaves like our old WNB series models with integer outputs (models numbers WNB-xx-xxx-FT10), then you should order a WNC-xx-xxx-FT10 Option BI. The Option BI WattNode meters are very similar to the original WNB series WattNode Plus models, but with a few changes:

  • New program ID: 9:00022:1500:0A:04:0B. Because there are some hardware changes, LonMaker® requires a new program ID.
  • New XIF (external interface) file
  • Energy and time of day are stored to non-volatile memory every 5 seconds. The old version stored these every 20 seconds.
  • The energy log has been removed (see our WattNode Logger for LonWorks if you need logging). The nviLogRequest and nvoLogData variables still exist, but do nothing.
  • The network variable list is identical to the original WNB series WattNode Plus with option I (Integer Output).
  • Firmware version 3.1x (3.13 as of March 31st, 2009)

Network Variable Scaling

See the WattNode LonWorks Option B manual for a list of all variables and SNVT types. The integer types used with Option BI are sometimes scaled for better resolution. Normally, tools like LonMaker® will automatically handle the scaling, but if you are looking at unscaled values, the following lists indicates the correct scaling.

  • SNVT_elec_kwh is in units of 1.0 kilowatt-hours (so a reading of 23 = 23 kWh)
  • SNVT_power_kilo is in units of 0.1 kilowatts (so a reading of 45 = 4.5 kilowatts or 450 watts)
  • SNVT_volt is in units of 0.1 volts
  • SNVT_freq_hz is in units of 0.1 hertz
  • SNVT_amp is in units of 0.1 amps and ranges from -3200 to +3200
  • SNVT_pwr_fact is in units of 0.00005 (so divide by 20000 to get the power factor)

Note: the nciCtAmps are of type SNVT_amp with units of 0.1 amps, so if you need to set the CT amps to 50, the actual value written to nciCtAmps will be 500. As noted above, tools like LonMaker will automatically handle this conversion for you.


See Also