Ladder Logic
MVI56-DNP
♦
ControlLogix Platform
User Manual
DNP 3.0 Server
Page 54 of 171
ProSoft Technology, Inc.
July 21, 2011
3.1 DNP
Module
The sample ladder logic relies heavily on the use of User-defined Data Types
(UDTs) to help group and structure the wide variety and volume of data and
control features the module offers. Lower-order UDT structures are often
embedded in higher-order structures to help further organize data into more
easily understood data collections.
All data and control parameters related to the MVI56-DNP are contained in
twenty-one (21) User-defined Data Types (UDTs). The
DNPModule
UDT is the
primary, top level data structure in which all other lower-order data types are
grouped and organized. All groups branch down from this UDT.
To utilize all the features and functions of the module, an instance of each data
type is required. This is accomplished by declaring controller tag variables using
these data types in the Controller Tags Edit Tags dialog box. You can start with
the sample ladder logic and build your application around the sample; or, you can
duplicate the I/O Configuration, UDTs, Controller Tags, and Ladder Logic (Tasks)
from the sample program into your existing application project.
Some UDTs hold process or status data
(Module Data Objects)
. This data can be
monitored and manipulated by your application-specific ladder logic program.
Other UDTs are used to store and organize the parameters needed for special
functions and control features
(Special Data Objects)
. All of these data types will
be discussed in more detail in succeeding topics.
