The DNP User Group published the following news on December 28th 2016:
The DNP Technical Committee has released the following Technical Bulletin (TB):
- TB2016-005 Indicating Invalid Floating-point Data in Object Group 0 Variations
TB2013-004 introduced some new Object Group 0 Variations that are used to report GPS data from an outstation (latitude and longitude). Questions arose about how an outstation should use these objects if it cannot get a GPS fix to the required number of satellites and thus cannot determine valid values of latitude and longitude.
The new 2016 TB (dated December 14th 2016) introduces the IEEE 754 standard of “quiet not a number” qNaN to the DNP3 specification. This can be used in various DNP3 group 0 objects where the DNP3 standard specifies a floating point number is to be used but the outstation is unable to provide a valid number because the data is invalid, unreliable, unavailable, or otherwise of poor quality.
The DNP Technical Committee also updated TB2013-004, adding the use of qNaN, and published the revised document as TB2013-004a.
How does this affect WITS users?
These Group 0 Object Variations are not mandatory in the WITS-DNP3 protocol so the Technical Bulletin has no impact on WITS users.
How does this affect WITS vendors?
WITS vendors that support and implement the Group 0 Variations should note the use of qNaN and provide updates to their devices as appropriate.
The DNP Technical Bulletin can be downloaded by members of the DNP User Group from www.dnp.org
Please email firstname.lastname@example.org if you have any questions.