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Two-Byte vs. Four-Byte Network Variables


Overview

All standard WattNode® for LonWorks® models use primarily four-byte SNVTs, such as SNVT_power_f, SNVT_elec_kwh_l. The old WNB-xx-xxx-FT10 models with the “integer output” or “Circon” option provided two-byte (16 bit) integer outputs instead. These same two-byte values are available with our present generation WNC-xx-xxx-FT WattNode for LonWorks meters by ordering them with “Option BI”.

Originally, the integer outputs were provided because Circon software did not support floating point values. However, there are a few other reasons for customers to order WattNode meters with Option BI:

  • Compatibility with Circon software or other software that doesn’t handle floating point values.
  • Some LonWorks controllers only log integer or two-byte values.
  • Cannot handle the new SNVT_elec_kwh_l four-byte (32 bit) integer energy SNVT type.
  • Have problems handling very large energy values and prefer the 50,000 kWh rollover of the Option BI.

Notes

  • Currently, the Option BI model is not LonMark® compliant, because it emulates the SNVT list of the old WNB-xx-xxx-FT10 model with integer outputs.
  • Currently, CCS does not offer our WattNode Logger for LonWorks with Option BI.