Data Sheet

GNM3D and GNM3T Series Communication Protocol
7
2 TABLES
2.1 Data format representation
The variables are represented by integers or floating numbers, with 2’s
complement notation in case of
“signed” format, using the following:
Format
IEC data type
Description
Bits
Range
INT16
INT
Integer
16
-32768 .. 32767
UINT16
UINT
Unsigned integer
16
0 .. 65535
INT32
DINT
Double integer
32
-2
31
.. 2
31
UINT32
UDINT
Unsigned double integer
32
0 .. 2
32
-1
UINT64
ULINT
Unsigned long integer
64
0 .. 2
64
-1
IEEE754 SP
Single-precision floating-point
32
-(1+[1 –2
-23
])x2
127
.. 2
128
For all the formats the byte order (inside the single word) is MSB->LSB. In INT32, UINT32 and UINT64
formats, the word order is LSW-> MSW.
2.2 Geometric representation
According to the signs of the power factor, the active power P and the reactive power Q, it is possible to
obtain a geometric representation of the power vector, as indicated in the drawing below, according to
EN 60253-23:
Fig. 2 : Geometric Representation
a = Exported active power
b = Imported active power
c = Imported reactive power
d = Exported reactive power
According to the measurement mode (easy connection or bidirectional), the following sign convention is
used in
GNM3D and GNM3T series.
- Eas
y connection mode
o I always >0
o P always >0
o
kWh always increasing (GNM3T and GNM3D version)
o kvar
h increases only when Q>0
o PF only with C and L (without sign) indication
- Bi
directional mode)
o I < or >0 (with indication of “-“ sign)
o P < or >0 (with indication of “-“ sign)
o kWh+ increasing only when P > 0 (only when Measurement menu is set to “B" in the
GNM3D non-MID version or in the MID version GNM3D-LP)
o kWh- increasing only when P < 0
o kvarh+ increasing only when Q > 0
o kvarh- increasing only when Q < 0
o PF with ±C or ±L indication