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D.6
SEL-787 Relay
Instruction Manual
Date Code 20081022
DNP3 Communications
DNP3 in the SEL-787
TCP/UDP Selection
The Committee recommends the selection of TCP or UDP protocol as per the
guidelines in
.
DNP3 in the SEL-787
The SEL-787 is a DNP3 Level 2 remote (slave) device.
Data Access
lists DNP3 data access methods along with corresponding SEL-787
settings. You must select a data access method and configure each DNP3
master for polling as specified.
In both the unsolicited report-by-exception and quiescent polling methods
shown in
, you must make a selection for the PUNSOL
n
setting.
This setting enables or disables unsolicited data reporting at power up. If your
DNP3 master can send a message to enable unsolicited reporting on the
SEL-787, you should set PUNSOL
n
to No.
While automatic unsolicited data transmission on power up is convenient, this
can cause problems if your DNP3 master is not prepared to start receiving data
immediately on power up. If the master does not acknowledge the unsolicited
data with an Application Confirm, the device will resend the data until it is
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
Access Method
Master Polling
SEL-787 Settings
Polled static
Class 0
Set ECLASSB
n
, ECLASSC
n
,
ECLASSA
n
to 0; UNSOL
n
to No
Polled report-by-
exception
Class 0 occasionally, Class 1,
2, 3 frequently
Set ECLASSB
n
, ECLASSC
n
,
ECLASSA
n
to the desired event
class; UNSOL
n
to No
Unsolicited report-
by-exception
Class 0 occasionally, optional
Class 1, 2, 3 less frequently;
mainly relies on unsolicited
messages
Set ECLASSB
n
, ECLASSC
n
,
ECLASSA
n
to the desired event
class; set UNSOL
n
to Yes and
PUNSOL
n
to Yes or No
Quiescent
Class 0, 1, 2, 3 never; relies
completely on unsolicited
messages
Set ECLASSB
n
, ECLASSC
n
,
ECLASSA
n
to the desired event
class; set UNSOL
n
and PUNSOL
n
to Yes.
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 below, 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.
Содержание SEL-787
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