0 Replies Latest reply on Aug 18, 2017 9:40 AM by mnudel RSS
    mnudel Explorer

    What is a relationship between OPC DA client's timestamp and PostgresSQL "time" field?

    Hi there, I'd like to understand the difference between the timestamp of the property data-change event acquired by the OPC DA client and the "time" (timestamp without timezone) field of the value stream.

     

    To illustrate, consider the following scenario. Machine is running with the OPC DA client installed (version 5.7). A property has changed its value at 09:20 am. Corresponding timestamp would look something like: "2017-08-18 09:20:00". The database has registered this event, however, the timestamp is different - "2017-08-18 10:20:00" (1h ahead).

     

    Having read the following article and documentation I assumed that the timestamp sent by the OPC DA client must be of the following type:"2017-08-18 09:20:00Z" (GMT timezone). Since there is no time difference between UTC and GMT, PostgresSQL would store this timestamp internally. Whenever the property value is queried, the timestamp will be converted to the appropriate timezone (as set in "postgresql.conf"). Since my PostgresSQL is set to be "Europe/London", the timestamp is therefore: "2017-08-18 10:20:00".


    Is the above observation true? Thanks.