Tech Note 89: How to Implement Time Considerations with Wonderware Historian and IDAS Systems
When working with Wonderware Historian and IDAS, it is important to take time into serious consideration. With IDAS historical data storage there is a term called the “Real-Time Window”, which is a period of time behind and ahead of the Wonderware Historian system time, where values coming into the system are considered “valid” and will be stored properly. With Wonderware Historian the real-time window can be any value coming into the system between -30 seconds and +999 milliseconds. Time offset and discarded data can be a result of improper time synchronization. The purpose of this document is to help identify time issues between your Wonderware Historian and remote IDAS machines, and correct them.
NOTE: This does not apply to MDAS storage. MDAS design is specific to late data.