9.28
SEL-2032
Communications Processor
Instruction Manual
Date Code 20120126
Protocols
Serial Distributed Network Protocol (Serial DNP3)
Installation
If you are using the SEL-2032 in a point-to-point DNP3 connection, simply
connect Port 16 to your DNP3 master. If you are using the SEL-2032 in a
multidrop configuration, you will need to connect a transceiver to Port 16. If
the transceiver has a Carrier Detect (CD) signal, connect it to the Port 16 CTS
input. Otherwise, connect RTS to CTS at Port 16. If the transceiver requires a
signal to enable its transmitter, you can use the RTS output on Port 16 for that
function.
Configuration
lists all of the DNP3-related settings and their functions. In
order to best configure the SEL-2032 for optimal DNP3 operation, you will
need to understand the basics of DNP3 and the capabilities of your DNP3
master.
Data-Link Operation
There are two important decisions you need to make about your data-link
layer operation. One is how you want to handle data-link confirmation. The
other is how you want to handle data-link access.
The DNP User’s Group recommends that you disable data-link confirmation
altogether, which significantly reduces communications overhead. If you
enable data-link confirmation, you must set the data-link time-out long
enough to allow for the worst-case response of your master plus transmission
time.
When the SEL-2032 decides to transmit on the DNP3 link, it has to wait if the
physical connection is in use. The SEL-2032 monitors physical connections
by using both its CTS input (treated as a carrier detect) and by monitoring for
incoming characters. Once the physical link is idle, as indicated by CTS being
deasserted and no characters being received, the SEL-2032 waits a
configurable amount of time before beginning a transmission. This hold-off
time will be a random time between the MIN_DELAY and MAX_DELAY
setting values. This hold-off is random so multiple devices waiting to
communicate on the network will not continually collide.
Data Access Method
Based on the capabilities of your system, you will need to determine how you
want to retrieve data on your DNP3 connection.
summarizes the
main options, from least to most efficient, and indicates the key related
settings.
Table 9.15
Data Access Methods
(Sheet 1 of 2)
Data Retrieval Method
Description
Relevant SEL-2032 Settings
Polled Static
The master polls for
static (Class 0) data only.
Set CLASS = 0,
Set UNSOL_REP = N.
Polled
Report-by-Exception
The master polls
frequently for event
data and occasionally
for static data.
Set CLASS to a non-zero
value, Set UNSOL_REP = N.
Summary of Contents for SEL-2032
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