Aggregation - Bring Data from Multiple Sources into One OPC Server
OPC Aggregation is the bringing together of data from different OPC Servers into a single data source, so that one or more OPC Clients can access this data through a single common interface.
So why would you use Aggregation?
One of the advantages of Aggregation is that it can be used to insure a common and consistent update rate is passed to the OPC Server and thus to the hardware devices. You may not realize this but most OPC servers decide what rate to poll the hardware devices based on the requested update rate from the OPC Client. If you have capacity limitations in your control network and want to insure a random OPC client doesn’t come in and overload it with an unreasonable update rate, then OPC Aggregation is a way to accomplish some regulation of traffic on your control network.
Aggregation also allows you to get OPC data to multiple OPC Clients when the OPC server only allows a single OPC Client connection for technical or commercial licensing reasons. Similarly, some OPC clients are licensed based on the number of servers they connect to and the costs can become enormous if you have multiple OPC servers you need to get data from. Aggregation helps solve this problem as well.
Aggregation also helps with OPC Servers that create additional connections to the PLC for each client connection or don’t optimize request well by insuring that only the OPC Aggregator’s requests are making direct connections to the PLCs, DCS, or other control hardware. At the end of the day, using OPC Aggregation can help you reduce network traffic, improve system performance, and save you time and money in the implementation of your systems. The Cogent DataHub can also be used to Aggregate information from other sources, not just OPC DA.
Using the TOP Server for Aggregation
You can also use the TOP Server for OPC DA aggregation using the OPC DA Client Driver – click her for more details.