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C: Shark® 270 Meter DNP Mapping
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• The settings are somewhat different in the case of Analog Inputs and Binary
Counters. Since the DNP3 points are a mapped version of the Modbus registers
in the meter, and since the Modbus register Type for some readings can be either
float, 16 bit integer, or 32 bit integer, the Shark® 270 meter’s DNP3 implemen-
tation provides the flexibility to set up different default variations depending on
the mapped Modbus register’s Type. See the following examples.
Use example 1:
The user wants to read Voltage Van (currently 112.55 V) and Phase Vab (currently
1800) as integers, so the user sets the default variation as integer. Both magnitudes
are Analog Inputs for DNP3, but the Voltage Van Modbus register is a float value and
the Phase Vab Modbus register is a 16-bit integer. In this case, the user could config-
ure Voltage Van to be mapped into Analog Input Point #0 and Phase Vab into Analog
Input Point #1, and then configure the Default Variation for Analog Input Float to use
Variation #5 (short float), and the Default Variation for Analog Input 16-bit to use
Variation #2 (16-bit integer). In this way, the actual register value is preserved and
the meter can reply to a request with the default variation for these points: the Volt-
age Van will be replied as a float 112.55 (not losing precision) and the Phase Vab as
the integer 1800 (also in its native format), supplying the optimized data read.
Use example 2:
The data and registers to be read are the same as in the first example, but the user
wants to read any Analog Input as 16-bit integer, whatever the Type of the original
Modbus register (float, 32-bit, 16-bit). Again, the user could configure Voltage Van to
be mapped into Analog Input Point #0 and Phase Vab into Analog Input Point #1, but
configure the Default Variation for both Analog Input Float and Analog Input 16-bit to
use variation #2 (6-bit integer). The meter can then reply to a request with the
default variation for these points: the Voltage Van will be replied as the 16-bit integer
112 (losing decimals due to conversion) and the Phase Vab as 1800 (in its native for-
mat). Although conversion can cause some loss of precision, the meter’s reply is
much easier to process since the format of all the points is known.
