ProSoft Technology MVI69-DNPSNET - Manual (Page 84)

MVI69-DNPSNET ♦ CompactLogix or MicroLogix Platform Reference
Distributed Network Protocol Interface Module
Page 84 of 119 ProSoft Technology, Inc.
November 3, 2008
DNP Digital Input Data
This data type stores the binary value of 1 or 0. The size of this data area is
determined from the configuration parameter Binary Inputs (number of words,
each containing 16 binary input points). These data are transferred to the module
from the PLC using the read operation. Therefore, these data are read-only for
the module and the DNP master unit communicating with the module. When the
module receives a new block of this data from the PLC, it compares the new
values to those currently in the database. If there is a change in any of the data,
the module will generate an event message for the points that change.
The remote DNP master unit can read the current status data and the event data
from the module. Event messages generated by the module can be retrieved
using a poll for Class 2 data, as all digital input events are considered a Class 2
data type. If unsolicited message generation is enabled in the application, the
events will automatically be sent by the module to the DNP master unit when the
maximum event count for Class 2 data is reached or when the timeout for
unsolicited messages is exceeded. A data flow diagram for the digital input data
is shown in the following figure.