ABB 615 Series Manual page 16

Section 2
DNP 3.0 overview
10
• Exchange of SDUs between peer DNP 3.0 data links
• Error notification to data link user
• Sequencing of SDUs
• SDU delivery quality.
Link-layer confirm usage is deprecated. See DNP Technical Bulletin TB1998-0402,
section 3 for details at www.dnp.org
Transport pseudo-layer
To support advanced RTU functions and messages exceeding the maximum data link
frame length, a transport pseudo-layer which implements message assembly and
disassembly services was adopted. This pseudo-layer is actually a super-data link
transport protocol, which is normally included in some OSI protocol data links.
Transport functions:
• Fragmenting user data into one or more data link frames and transmitting the
data to the data link layer
• Assembling the data link frames received from the data link layer into user data
• Controlling all aspects of the data link excluding data link configuration.
Transport responsibilities:
• Exchange of SDUs between peer DNP 3.0 transport pseudo layers
• Error notification to transport user
• Sequencing of SDUs.
Application layer
The application layer is responsible for performing operations on data objects defined
by the device or on the device itself. These operations can be: returning actual values
(read function), assigning new values (write function) if the object represents control
points, arming and energizing the output point (select, operate or direct operate
functions) and if counters are used, storing actual values (freeze functions) and
clearing the counters.
Many objects may be assigned to event classes. The DNP 3.0 protocol defines four
classes; 0 for static data and 1, 2 and 3 for event data.
Binary inputs and analog inputs may be assigned to class 0. Binary events and analog
events may be assigned to classes 1, 2, or 3. If a binary event or analog event is in
class 1, 2, or 3, the corresponding input should be in class 0. The configuration
GUI provides this behavior. Any point which is not in class 0 will not be returned in
a class 0 scan, however, its static value may be read explicitly.
In the present implementation, the binary output object may not be assigned to
generate events in classes 1, 2 or 3. Instead, the outputs are available as binary inputs,
which may then be assigned to generate events. The actual status of the binary outputs
can be read from the binary inputs. A read of the binary outputs returns the last value
.
Communication Protocol Manual
1MRS756709 A
615 series