DNP3 Manual
M6xxD/EN M/B
M6xx
Page 10
1.5.3 Tag Registers
The M6xx meters provide a "TAG" BINARY OUTPUT for user identification purposes. DNP sessions
have an additional tag register (“Tag Register 1”). An
ANALOGUE OUTPUT BLOCK
can be issued to
either point to write a number from 0 to 65,535 in a tag register. Tag registers are also writeable
through the web interface.
1.6 Converting Data to Engineering Units
As mentioned in Section 1.5, the majority of the data is stored in a normalized 2's complement format.
When displaying these values at another location, it may be desirable to convert this format into
engineering units. This conversion is readily accomplished using the following simple scaling
equations:
BASIC EQUATION FOR NORMALIZED ANALOGUE INPUTS:
32768
SEC O N D ARY
Value
N orm alized Scale Factor
Engineering U nits
D efault Full Scale
Scale Factor D ivisor
The
Value
referred to in the equations would be the value stored in the point that you wished to
convert to engineering units. For example if you wanted to convert Phase A Amperes into engineering
units, Value would be the value in ANALOGUE-INPUT point.
ENERGY
is stored as 32-BIT values in static COUNTER points. Energy values are in units of
PRIMARY kWh or kVARh.
FREQUENCY
is stored as a single binary value that is the actual frequency times 100.
POWER FACTOR
is stored as the value times 1000. Negative power factors indicate that the VARs
are positive. The sign of the Power Factor is the inversion of the Exclusive-OR of the Watts and VARs
(i.e. if either or both of the Watts or VARs are negative, then the Power Factor will be negative).
