ProSoft Technology MVI69-DNPSNET - Manual (Page 87)

Reference MVI69-DNPSNET ♦ CompactLogix or MicroLogix Platform
Distributed Network Protocol Interface Module
ProSoft Technology, Inc. Page 87 of 119
November 3, 2008
DNP Analog Input Data
This data type stores analog data with a data range of 0 to 65535 or -32768 to
32767. The size of this data area is determined from the configuration parameter
Analog Inputs. 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. 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 dead-band parameter configured for the module determines the
variance required for the event message.
The DNP master unit can read the current value data and the event data from the
module. Event messages generated by the module can be retrieved using a poll
for Class 3 data, as all analog input events are considered a Class 3 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 3 data is reached or when the timeout for unsolicited
messages is exceeded. A data flow diagram for the analog input data is shown in
the following figure.