Reference MVI71-DNPSNET
♦
PLC Platform
Distributed Network Protocol Interface Module
ProSoft Technology, Inc.
Page 87 of 100
September 22, 2008
Functionality
This phase of design defines the features of the DNP Level 2 Subset supported
by the module and to be utilized in the specific application. For example, will the
unit use unsolicited messaging? Coordination with the DNP master developer is
required to verify that the host will support the functionality you select. The
features that must be defined in this design step are as follows:
Will analog events be returned with or without a time value?
Will events be logged before time synchronization has occurred?
Will the module start with database values initialized by the processor?
For a complete description of the module configuration, refer to the
Module
Configuration
section.
Data Transfer at Startup
The module can be configured to have the internal databases initialized with data
contained in the processor. This feature requires ladder logic if the block-transfer
interface is utilized. Data to be initialized are as follows: Binary and Analog
Output data. This feature can be used to bring the module to a known state (last
state set in controller) when the module is first initialized. For example, in order to
have the module startup using the last set of binary output values and setpoint
values (analog outputs), enable this feature.
If this feature is implemented, the module will request the data from the
processor. If the side-connect interface is employed, the module will read this
data directly from the user data files. If the block transfer interface is used, ladder
logic must handle the blocks requested by the module (1000 to 1148) based on
the modules configuration values for the write block data. When the block is
requested, the module must place the correct data in the block and return the
block to the module. The module will receive the data and initialize the output
values. Each block required by the module for initialization will be requested.
5.9.2 Module
Operation
After the system has been designed and the system is set up, the module will be
ready to operate. When the module is first initialized, it will read the configuration
file (DNPSNET.CFG on the module's Compact Flash Disk). After the file is
processed, the module will use the data to set up the data structures of the
application. If any errors are encountered during the initialization process, the
default value for the parameter will be assigned and used.
The module will next check if the output initialization feature is utilized. The
option permits the PLC to set these read-only data at startup. There is no static
memory available on the module to remember the last values for these data
types. In order to prevent a "shock" to the system at boot time, this option can be
used to set the module's database to the last transferred set of data. If this option
is enabled, the module will request the binary and analog output from the PLC.
Summary of Contents for InRax MVI71-DNPSNET
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