ProSoft Technology MVI46-DNP - Manual (Page 65)

Reference MVI46-DNP ♦ SLC Platform
Master/Slave Communication Module
ProSoft Technology, Inc. Page 65 of 143
August 23, 2007
The following illustration shows the interaction of the binary and analog output
points with the databases.
The DNP database consists of data from the DNP master on the slave port. This
data is passed to the SLC and to the IED units through the command list. The
IED database contains control data generated in the SLC. This is the only data
path for SLC control of IED units on the DNP master port. A command must be
set up to handle the transfer of data from the IED database to the IED unit. The
last value databases are used for exception processing of control commands.
Commands can be configured to only generate a message if there is a change in
the database. The current values are compared against the last value database
to recognize the changes. When a change is recognized, the DNP master port
executes a command to the specific IED unit containing the new data.
Data Transfer Interface
Data is directly transferred between the module and the SLC through M-files (M0:
and M1:). The module automatically interfaces the internal DNP and IED
databases to the M-files. You must construct ladder logic to read and write the M-
file data for use by the SLC. All configuration and command control data is stored
in the M0: file.