3.7.2
Analog input signal scaling for DNP3 master presentation
GUID-CAC9E9AA-B58D-4A9E-9337-914BE52A9AB8 v5
The presentation of an analog value in a telecontrol protocol varies between the
different protocols and also with the age of the used protocol version. The range is
from a simple 8 bit integer up to a double precision floating point. Internally in the IED
many calculations are floating points.
PCM600 supports the re-scaling and the justification to the register presentation given
by the project demands.
presents a typical example of a signal flow in the IED from the CTs, VTs to
the DNP3 master. The CT, VT is connected to the IED by the transformer module
TRM. The SMAI function block is a preprocessor to calculate, check the signals for
further use in application function blocks of type MMXU. MMXU calculates the RMS
values for the most used analog signals like, V, I, P, Q, for example. The RMS values
are available in floating point presentation as output signals of function blocks of type
MMXU.
ANSI13000288-1-en.vsd
SMAI
MMXU
or other
application
functions
DNP3
master
DNP3
Comm.
Interface
Scaling to
DNP3
demands
Source values
Destination Values
Equation mode
Reg. justification
DNP3
’DEVICE PROFILE’
Analog Input Points
DNP3
Register length
(Float, 32, 16, 12, 8 bit)
T
R
M
ANSI13000288 V1 EN-US
Figure 3:
PCM600: typical example of DNP3 scaling
The actual DNP3 specification defines 6 variations for the presentation of an analog
value:
•
Variation 1 - 32-bit with flag
•
Variation 2 - 16-bit with flag
•
Variation 3 - 32-bit without flag
•
Variation 4 - 16-bit without flag
•
Variation 5 - single-precision floating point with flag
•
Variation 6 - double-precision floating point with flag
The IED supports all 32-bit and floating point variants without any additional scaling
configuration. This is given as long as the
MaxSourceVal
(as it is given in the IED as
Section 3
1MRK 511 413-UUS B
Vendor-specific implementation
22
650 series 2.2 ANSI
Communication protocol manual
