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Can the ensure the time alignment automatic? How does the openPDC achieve?

Jul 27, 2013 at 10:24 AM
Hi all:
Network Transmission speed is different between two data sources。How will we ensure the time alignment when the data reach the openPDC 。
Thanks
Wen
Jul 30, 2013 at 2:13 PM
Edited Jul 30, 2013 at 2:18 PM
Network transmission speed really only has two measurable parameters: bandwidth and latency. Bandwidth simply limits the "volume" of data that that be transmitted through a connection and latency simply is the "delay" in transmission due to distances and number of intermediate connections (e.g., routers, firewalls, etc.)

Since you will only be able send a volume of data that your connection supports, this parameter is not a concern for the openPDC. The openPDC does care about latency though.

Normally several data sources over different network connections will have different latencies - to make sure even the most delayed (i.e., slowest arriving) data is included in the time-alignment, you can adjust the concentrator's "lagTime" parameter (see: http://openpdc.codeplex.com/wikipage?title=Connection%20Strings#ActionAdapterBase) to accommodate even the slowest data.

The openPDC concentrator (and any other concentrator for that matter) must wait for the slowest data to arrive in order to include the values in a combined time-aligned outgoing stream.

Note that this is only important when you want to create a time-aligned set of data for analysis or frame-centric data transmissions. The openPDC is a measurement based processing system so even very slow arriving data that may have missed the time-alignment window can still get archived or transmitted through measurement based protocols (e.g., the Gateway Exchange Protocol).

Hope that helps!

Thanks,
Ritchie
Jul 31, 2013 at 8:09 AM
thank Ritchie