Schweitzer Engineering Laboratories SEL-311C - Data Access Method; Table I.2 Data Access Methods

I.5
Date Code 20060320 Instruction Manual SEL-311C Relay
DNP Communications
Data Access Method
Data Access Method
Based on the capabilities of the system, it is necessary to determine which
method is desired to retrieve data on the DNP connection. The following table
summarizes the main options, listed from least to most efficient, and
corresponding key related settings are indicated.
Table I.2 Data Access Methods
Data Retrieval Method Description Relevant SEL-311C Settings
Polled Static The master polls for static
(Class 0) data only.
Set ECLASS = 0,
Set UNSOL = N.
Polled Report-by-Exception 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-Exception 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 messages
are desired to be sent.
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 messages are desired to be
sent.