ABB IEC 61850 Edition 2 Communication Protocol Manual page 46

Section 6
Data sets and control blocks
40
the GI is started. A running GI shall be stopped and a new GI shall be
started, when a new GI request is received while a GI is running.
• Purge buffer (valid only for BRCB)
• This BRCB attribute can be used by a client to clean the event buffer
from old events. The events are discarded on request of the client. This
feature can be used to delete old events not transmitted to the client due
to stopped communication. After the link is reestablished the client can
decide to clean the buffer or to receive the history.
Trigger Options
IEC 61850 has defined in total five different TrgOp. Three of them belonging to
data attributes and marked per data attribute in the column TrgOp of the CDC
tables in part 7–3. The other two belonging to the configuration of control blocks.
• dchg = data-change
• Whenever a process value has changed its value either binary or a
measurement a transmission is done.
• qchg = quality change
• Looking to the possibilities of the quality data attribute type (q) any
changes in the quality description will be transmitted.
• dupd = data value update
• This trigger option give the possibility to define that a transmission
should be done on a condition which can be controlled by the
application.
• integrity
• This trigger forces the transmission of all process values defined in the
data set when a timer value (the integrity period) expires.
• general interrogation
• This trigger is forced by the clients (= station level IED; NCC gateway,
station HMI, ...). Normally a GI is asked for, when the client and the
server start or restart a session. When the client is able to receive the
actual values and when the logical device has scanned all process values
at least once, an image of the actual process signal status can be
transmitted to the client.
Note that the possible trigger options for each attribute
are included and defined in the datatype template section
in SCL.
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