6.6.2 Introduction to OPC "H" A&E
OPC Historical Alarms and Events
Alarms and operating messages are stored in the database of the PCS 7 OS. With an OPC
A&E client, you can access archived messages via the OPC A&E server. When accessing
archived messages, the following methods are supported:
● Output of archived messages from a period in the past (history)
● Output of archived messages from a period in the past without an end time.
After outputting the archived messages, all additional newly generated messages are
automatically sent to the OPC A&E client.
Note
Reading archived messages using OPC "H" A&E is a Siemens expansion of the OPC A&E
standard.
Rule
After reading archived messages, you must not use the returned "ActiveTime" of a message
either for acknowledging the message or for tracking the transitions of the message. The
"ActiveTime" is not correct for archived messages. To make sure this is recognized, the OPC
A&E client must check the "EventType" of a message for the additional flag
"OPC_HAE_HISTORICAL_EVENTFLAG".
Note
You will find information on the additional flag in "Identifying archived messages".
6.6.3 Reading archived messages
Reading archived messages using OPC A&E
Archived messages of the PCS 7system are read by the OPC A&E client via the OPC A&E
server using filters. In this situation, the term OPC "H" A&E is also used in this documentation.
Apart from the standard filters, the following filters are also available with OPC "H" A&E:
● OPC_HAE_FILTER_BY_TIMEFRAME; corresponds to the function "ReadRaw" in OPC
Historical Data Access
● OPC_HAE_FILTER_BY_STARTTIME; corresponds to the function "AdviseRaw" in OPC
Historical Data Access
OpenPCS 7 interface
6.6 OPC Historical Alarms and Events (OPC "H" A&E)
OpenPCS 7
Function Manual, 05/2012, A5E02780178-02 75
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