Note
The following notation is supported for the "htStartTime" and "htEndTime" parameters:
● Relative notations, for example NOW
● Symbolic values, for example NOW, YEAR, MONTH
● Absolute UTC date/time specified according to XML notation:
"2011-09-10T10:00:00.000C".
The use of symbolic notation corresponds to the syntax of OPC Historical Data Access.
6.6.5 Read modes for archived messages
Read modes for archived messages
When reading archived messages, you can use the following read modes:
● Read
● Advise
"read" mode
With the "read" mode, archived messages are read from a defined period in the past. The read
order of the messages is always chronological for each OS server from which alarms are read.
By setting the start and end time, you can specify whether the oldest message is output first
or last. If the start time is lower than the end time, the oldest message is output last.
If you want to use the "read" mode, execute the following functions on the subscription:
1. SetFilter
2. Refresh
A "SetFilter" during the "Refresh" is discarded.
If you activate the subscription during "Refresh", it will not affect the running of the refresh.
The historical events are still transferred with the refresh ID. The newly generated events are
transferred according to the standard behavior of an active subscription:
● Taking into account the set filter values with the exception of the "historical" source
"OPCHAEServer"
● Without refresh ID
OpenPCS 7 interface
6.6 OPC Historical Alarms and Events (OPC "H" A&E)
OpenPCS 7
78 Function Manual, 05/2012, A5E02780178-02
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