Applies To:
  • CitectSCADA 3.x, 4.x, 5.x

How does the Time Server feature in Citect actually work? 

You enable 1 computer on the Citect network to be a time server (parameter [time]Server=1, set by the computer wizard). The best computer is the I/O Server as this will be always be connected to every Citect on a system, rather than say Alarm server which may only be talking to half the clients. When a Client starts up the time server will sent a time sync message. Also at the [time]pollTime rate (default 24 hours) the time server will send a time sync message to all it's connected clients to adjust their time. When a Citect gets a time sync message it checks to see if the time sync in enabled (parameter [time]Disable=0). If disabled the Citect ignores the time sync message. If enabled the Citect will check if the new time is out side of the deadband time (parameter [time]Deadband=10). If the time is outside of the deadband the Citect will adjust its clock to the new time. The deadband is used to stop constant small changes in the time. When the time is changes, Citect must re-sync all of its time related tasks and this can take a long time (typically only on the trend server as must re-sync all the trends).

If the parameter [time]RTsync is set on the time server then the time server will re-sync it's time to the hardware clock before it sends out a time sync message. This allows for the case when the Windows clock has drifted against the hardware clock.