Clock drift check

The Clock Drift Check ensures that there are no drifting of clocks between the field and the host. This check is performed prior to loading the data into the system, and only if the Clock Synchronization Check is successful.

Note: This is performed by the SCADA system and the results are passed to the Measurement system for display.

This check applies to current time retrieved from all field telemetry equipment. The following algorithm is used to detect drifting between the clocks:

Tol < (( Host + Offset ) – Field) /60)

Where:

• Host = Clock time on the server at Greenwich Mean Time (GMT) (seconds).

• Offset = Difference between GMT and the field equipment’s time zone (seconds).

• Field = Clock time on the field equipment, local to the device’s time zone (seconds).

• Tol = Tolerance acceptable for the data (minutes).

If the check returns a false condition, a problematic context is raised and data processing continues.