ProSoft Technology 5201-DFNT-DNPS - Manual (Page 55)

Reference ProLinx DNPS ♦ ProLinx Gateway
User Manual DNP 3.0 Slave
ProSoft Technology, Inc.
Page 55 of 86
December 1, 2009
3.3.6 Designing the system
System design defines the data requirements of the system, communication
parameters, and module functionality. The application developer should refer to
the person responsible for the DNP master and slave device configurations to
verify that the functionality and data types required for the whole system are
consistent. Review the DNP Device Profile and DNP Subset documentation for a
definition of the level of DNP support offered by the module.
The following topics describe each element of system design.
DNP Functionality Review
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. If a DNP
master port is to be used, the parameters required to communicate with the slave
devices must be known and considered in installing and configuring the module.
The features that must be defined in this design step are as follows:
DNP Feature Discussion
Is collision avoidance
required for the primary DNP
port? Collision avoidance is required when unsolicited messaging is
used. Any node on the network (master or slave) can transmit a
message when data is ready. Collision avoidance prevents two or
more units from transmitting data at the same time. This feature
requires special cabling and timing considerations. It will only
operate in RS-232 mode, and is not supported in RS-485 or RS-
422 modes.
Will the module use events
and the Report by Exception
feature? If the DNP Slave driver will generate event messages, they must
be retrieved from the module using class polls or polls for the
specific event objects. Refer to Event Size Computation (page 67)
for computing event size for digital and analog inputs.
Will analog events be
returned with or without a
time value? The default for analog events is to return them without time. This is
as specified in the DNP Subset document. The module supports
analog event reporting with time. This is selected setting bit 5 in the
configuration word (offset 21) for the module.
Will events be logged before
time synchronization has
occurred? This feature will avoid logging events without the proper date and
time stamping. When the DNP slave driver is initialized, it will have
the IIN bit set to request time synchronization from the remote
master unit. The master must synchronize the time before the
module will generate events. This feature is selected using bit 8 in
the module’s configuration word.
Will unsolicited messages be
used? If so, how may for
each class before triggering
and what is the delay time? Unsolicited messaging provides the means for a slave unit to send
event data asynchronously to the master unit without a request
from the master. This requires the use of collision avoidance to
prevent two or more units from transmitting data on the network at
one time.
What will be the memory
mapping for the DNP and IED
memory areas? There are many databases maintained within the module for all the
specific DNP data types and for the virtual slave unit simulated in
the module. For successful application of the module, an
understanding of the databases is required to carefully design
them.