Opc server for ac 800M, Installation and Configuration
Setting Cache Update Rate
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- Điều hướng trang này:
- Settings > Update Rate...
- Actual
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Setting Cache Update Rate The cache update rate controls how often the OPC Data Access Server updates its internal cache with data from a certain controller. The cache update rate limits the update rate an OPC client can have on an OPC group. To ensure that subscribing OPC clients can access changed values at their requested update rate, the time (value) for cache update rate should be set shorter than the fastest OPC group update rate. To set the update rate, open the Update Rate dialog box by selecting Settings > Update Rate... from the OPC Server Configuration Panel. Figure 6. Update Rate Dialog The OPC Server should always have its update rate set twice as fast as the OPC client(s) update rate. Settings > Update Rate is only available from the OPC Data Access Server, i.e. when the Data Access tab is selected. Section 2 Start-up and Configuration Setting Cache Update Rate 3BSE035983-510 27 To distinguish between fast and slow update rates there are five categories for simple values (integer, real, bool) and a separate category for strings. The values in the Requested column determines the update rate of the internal cache in the OPC server, i.e. how often items in each category are read from the controller. When OPC Server for AC 800M is started, the values are set to default values. The values in the Actual column shows the current update rate. This value will vary around the Requested value depending on the load. A zero value in this column means that there is no MMS communication for that category at the moment. The requested update rates must be given in ascending order, starting at the High category. The lowest permitted update rate value for any category is 50 ms. Example An OPC client creates an OPC group with an update rate of 1000 ms. This means that items added to this OPC group will be reported to the OPC client once every second. In the OPC server, the MMS communication for this group is put in the High category, which means that items in this category will be read from the controller every 500 ms. If any groups has been added, the update rate cannot be changed. The update rate configuration should therefore be made at start-up of the OPC Server for AC 800M, before any groups been added. Clock Synchronization Section 2 Start-up and Configuration 28 3BSE035983-510 tải về 0.83 Mb. Chia sẻ với bạn bè của bạn:
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