D.6
SEL-751A Relay Instruction Manual Date Code 20100129
DNP3 Communications
DNP3 in the SEL-751A
➤ TCP is strongly recommended for LANs
➤ User Datagram Protocol (UDP) may be used for highly reliable
single segment LANs
➤ UDP is necessary if broadcast messages are required
➤ The DNP3 protocol stack shall be retained in full
➤ Link layer confirmations shall be disabled
The Technical Committee has registered a standard port number, 20000, for
DNP3 with the Internet Assigned Numbers Authority (IANA). This port is
used for either TCP or UDP.
TCP/UDP Selection
The Committee recommends the selection of TCP or UDP protocol as per the
guidelines in Table D.4.
DNP3 in the SEL-751A
The SEL-751A is a DNP3 Level 2 remote (slave) device.
Data Access
Table D.5 lists DNP3 data access methods along with corresponding
SEL-751A settings. You must select a data access method and configure each
DNP3 master for polling as specified.
Table D.4 TCP/UDP Selection Guidelines
Use in the case of… TCP UDP
Most situations X
Non-broadcast or multicast X
Mesh Topology WAN X
Broadcast X
Multicast X
High-reliability single-segment LAN X
Pay-per-byte, non-mesh WAN, for example, Cellular Digital Packet Data
(CDPD)
X
Low priority data, for example, data monitor or configuration information X
Table D.5 DNP3 Access Methods (Sheet 1 of 2)
Access Method Master Polling SEL-751A Settings
Polled static Class 0 Set ECLASSBn, ECLASSCn,
ECLASSAn to 0; UNSOLn to No
Polled report-by-
exception
Class 0 occasionally,
Class 1, 2, 3 frequently
Set ECLASSBn, ECLASSCn,
ECLASSAn to the desired event class;
UNSOLn to No
NOTE: Because unsolicited
messaging is problematic in most
circumstances, SEL recommends
using the polled report-by-exception
access method to maximize
performance and minimize risk of
configuration problems.
NOTE: In the settings in Table D.5,
the suffix n represents the DNP3
session number from 1 to 3. All
settings with the same numerical
suffix comprise the complete DNP3
session configuration.
To Next Page
Loading...
