E.14
SEL-734 Meter Instruction Manual Date Code 20090730
Distributed Network Protocol
Ethernet Operation
Ethernet Operation
The SEL-734 supports two simultaneous DNP sessions including one DNP-IP
session. To enable DNP-IP, set the EDNP setting equal to 1. The SEL-734
DNP LAN/WAN implementation conforms to DNP3 Specification, Vol. 7,
Networking—Transporting DNP3 over Local and Wide Area Networks,
Version 2.0, Draft H, 15 December 2004. DNP sessions act as listening end
points as defined by the DNP LAN/WAN specification listed above.
The DNP-IP response is identical to the serial but requires the following
communication specific settings:
If the UNSOL setting is set to Y, the SEL-734 will transmit unsolicited data
when either of the following are true:
➤ Initialization is complete and DNPTR = UDP, or
➤ The master has established a session, if DNPTR = TCP.
Data-Link Operation
It is necessary to make two important decisions about the data-link layer
operation. One is how to handle data-link confirmation, the other is how to
handle data-link access.
If a highly reliable communications link exists, the data-link access can be
disabled altogether, which significantly reduces communications overhead.
Otherwise, it is necessary to enable confirmation and determine how many
retries to allow and what the data-link time-out should be.
The noisier the communications channel, the more likely a message will be
corrupted. Thus, the number of retries should be set higher on noisy channels.
Set the data-link time-out long enough to allow for the worst-case response of
the master plus transmission time.
When the SEL-734 decides to transmit on the DNP link, it has to wait if the
physical connection is in use. The SEL-734 monitors physical connections by
using CTS input (treated as a Data Carrier Detect) and monitoring character
Table E.6 DNP-IP Specific Settings
Setting Definition Range
Default
Value
EDNP Enable DNP-IP Sessions. Set this value
to 0 to disable DNP-IP in the SEL-734.
0–1 0
DNPNUM DNP TCP and UDP Port.Identifies the
TCP and UDP port between the master
and the SEL-734.
1–65534 excluding
20, 21, 502, and the
TPORT setting.
2000
DNPIP Master IP Address. Set DNPIP =
0.0.0.0 to accept requests from any
DNP-IP address.
zzz.yyy.xxx.www 192.168.0.3
DNPTR Transport Protocol. Selects between
TCP and UDP protocols.
TCP, UDP TCP
DNPUDP UDP Response Port. Selects the port to
which the SEL-734 responds. IF
DNPUDP = REQ, the SEL-734
responds to the port number from the
master's UDP request.
REQ, 1–65534 2000
Courtesy of NationalSwitchgear.com
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