ProSoft Technology MVI69-DNPSNET - Manual (Page 89)

Reference MVI69-DNPSNET ♦ CompactLogix or MicroLogix Platform
Distributed Network Protocol Interface Module
ProSoft Technology, Inc. Page 89 of 119
November 3, 2008
DNP Float Input Data
This data type stores float data. The size of this data area is determined from the
configuration parameter float 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 float 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 float input data is shown in
the following figure.