Read RSView Supervisory Edition Trending Best Practices text version

RSView Supervisory Edition Trending Best Practices

Common issues identified on configurations for Trends:

· · An unreasonable value is set for the refresh rate. o This can cause poor performance and/or memory related problems. The "Maximum Tag Update Rate" in the Display Settings of the graphic display is set to a value that is slower than the Trend Refresh Rate. o The trend chart will not refresh as expected because the display settings will take precedence over the trend settings. A graphic display contains one or more trend objects and the display settings are set for "Cache after Displaying and Always Updating". o If there are several displays in the HMI project with this setting and depending on the how the trend is loading computer resources, this will have the potential to slow overall HMI application performance. The trend has the Data Server set for "Poll Historical Data" and the "Buffer for extra data" is set to a large value. o This is an unnecessary use of extra memory. "Buffer for extra data" can be set to 0 as the historical data source will be the buffer. VBA code is used to interface with the Trend object. o If the code is poorly written and does not incorporate sufficient error handling then unexpected behavior can occur.

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How to optimize Trend configuration settings:

Trend Object Refresh Rate: · Optimizing the trend "refresh rate" setting is important for both the visibility of the charted data and the performance because it affects memory and other resources that get consumed on the computer. o Using an optimal refresh rate will provide an operator with a trend that provides a good view of the plotted data without consuming more computer memory and resources than is necessary. Trend charts will update more quickly when traversing historical data. Large increases to the refresh rate will increase the number data points plotted, but to the human eye the trend will appear virtually the same as it would with the slower (optimized) refresh rate. Formula: Optimized Refresh Rate = (X-Axis Time Span in Seconds) / (Width of Trend Object in Pixels).

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Trend Object Memory Consumption: · · Formula: Trend Memory = (Number of Pens) * (58 Bytes) * (Records per Second) * (X-Axis in Seconds) Formula: Buffer Memory = (Number of Pens) * (58 bytes) * (Buffer Size in # of Records)

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Refer to "File Attachments" on Knowledgebase Answer ID 39643 for a PDF document version of this information that has additional screen captures of the trend component settings.

Page 1 of 5 Answer ID 39463 - RSView Supervisory Edition Trending Best Practices http://www.rockwellautomation.com/knowledgebase/

Other notable Trend properties:

Trend Properties -> Display tab: · Buffer for extra data maximum is 32767 records per pen. o Only use the "Buffer for extra data" setting if the Data Server is set for "Real time data ". o If the Data Server is set for "Poll Historical Data", then set the "Buffer for extra data" to 0. The historical data source will be the buffer.

Trend Properties -> General tab: · · Real-time data server minimum refresh rate allowed is 50 milliseconds. Poll historical data server minimum refresh rate allowed is 1 second.

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Setting the pen width on a trend to a selection greater than 1 will consume more memory. Once a graphic display is closed it will release the trend buffer memory used by any trend objects that were contained in the display.

Page 2 of 5 Answer ID 39463 - RSView Supervisory Edition Trending Best Practices http://www.rockwellautomation.com/knowledgebase/

How to determine the Pixel Width of your Trend object: · Use your mouse to select the Trend object, then right-click and choose "Property Panel" · Choose from Studio menu: View -> Property Panel

Where to locate the graphic display setting for "Maximum Tag Update Rate": · Use your mouse to select a blank area of the display, then right-click and choose "Display Settings..." · Choose from Studio menu: Edit -> Display Settings...

The "Maximum Tag Update Rate" of the graphic display should be set to a value that is equal to or faster than the Trend Refresh Rate.

Page 3 of 5 Answer ID 39463 - RSView Supervisory Edition Trending Best Practices http://www.rockwellautomation.com/knowledgebase/

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Also attached to the Answer ID 39463 knowledgebase document is an Excel file titled "Trend Optimized Refresh Rate and Memory Consumption Calculator.xls". This excel file can be used to run quick calculations based on the potential settings for your trend properties.

Page 4 of 5 Answer ID 39463 - RSView Supervisory Edition Trending Best Practices http://www.rockwellautomation.com/knowledgebase/

Additional trend information can be found at: http://www.rockwellautomation.com/knowledgebase/ Answer ID 29753 · Displaying a historical trend that reads data from an ODBC database takes too long to populate the trend. Answer ID 38446 · How To Optimize the Viewing of Large Time Ranges in Historical Trends. Answer ID 38446 · The pen lines in TrendX display as stair steps instead of a smooth line. Answer ID 37110 · RSView SE Tips and Best Practices TOC

Page 5 of 5 Answer ID 39463 - RSView Supervisory Edition Trending Best Practices http://www.rockwellautomation.com/knowledgebase/

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