E.15
Date Code 20090730 Instruction Manual SEL-734 Meter
Distributed Network Protocol
Data Access Method
receipt. Once the physical link goes idle, as indicated by CTS being deasserted
and no characters being received, the SEL-734 will wait a configurable
amount of time before beginning a transmission. This hold-off time will be a
random value between the MINDLY and MAXDLY setting values. The
hold-off time is random, which prevents continual collisions resulting from
multiple devices waiting to communicate on the network.
Data Access Method
Based on the capabilities of the system, it is necessary to determine which
method you want to use for retrieving data on the DNP connection.
Table E.7 summarizes the main options, listed from least to most efficient, and
corresponding key related settings are indicated.
Device Profile
Table E.8 contains the standard DNP3 device profile information. Rather than
checkboxes in the example Device Profile in the DNP3 Subset Definitions,
only the relevant selections are shown.
Table E.7 Data Access Methods
Data Retrieval
Method
Description
Relevant SEL-734
DNP Settings
Polled Static The master polls for
static (Class 0) data only
Set ECLASS = 0
Set UNSOL = N
Polled
Report-by-Exce
ption
The master polls
frequently for event data and
occasionally for static data
Set ECLASS to a non-zero value,
Set UNSOL = N
Unsolicited
Report-by-Exce
ption
The slave devices send
unsolicited event data
to the master and the
master occasionally sends
integrity polls for static data
Set ECLASS to a non-zero value
Set UNSOL = Y
Set NUMEVE and
AGEEVE according to how
often you want to send messages
Quiescent The master never
polls and relies on
unsolicited reports only
Set ECLASS to a non-zero value
Set UNSOL = Y
Set NUMEVE and
AGEEVE according to how
often you want to send messages
Table E.8 SEL-734 DNP3 Device Profile (Sheet 1 of 2)
Parameter Value
Vendor name Schweitzer Engineering Laboratories
Device name SEL-734
Highest DNP request level Level 2
Highest DNP response level Level 2
Device function Slave
Notable objects, functions, and/or
qualifiers supported
Supports enabling and disabling of
unsolicited reports on a class basis
Courtesy of NationalSwitchgear.com
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