Quote:
'Why would the "actual time that the alarm occurred" be different from the time that the system clock gives you What better source for a timestamp do you have '
- Because the Playback server is isolated and standalone. It is not the same machine (replica) that originally processed the alarm when it happend.
I wish I could show you the system topology herein, but here is a case:
1) On our network, a NTP server, some PLC's, the sniffer and 'server for Ifix SCADA' is connected
2) On 17:00:00 local time an alarm occurred and this alarm is time stamped on the 'server for Ifix SCADA' (upon arrival) at 17:00:00
3) At 18:00 we extract data from the sniffer for period 16:59:00 to 17:01:00
4) We then start a playback of this 2 min. long stream at 17:59:00 onto an 100% replica machine of the 'server for Ifix SCADA'
5) During playback, the alarm will be triggered and time-stamped by the Ifix SCADA apps. 18:00:00 which is wrong, cause the actual time of the alarm occurred 17:00:00
6) If we turn back clock to 16:59:00 (1 hour) at the moment of starting the playback the alarm will be activated 17:00:00 - now the time is correctly given.
Hope it is somewhat clearer
frode
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