I am new at this, so aplologies if I am not clear in my question.
I have a screen in RTMC Dev Pro with a digital display which displays a calculated value based on data from a single data file. Part of the calculation is a check on the timestamp of the data file, compared to the server time to insure that the displayed value is never more than 6 minutes old (the data file is updated every 5 minutes). If the data from the data file is less than 5 minutes old, the calculated value is displayed. If the data from data file is older than 6 minutes,the result of the calculation is "Not Available".
Works like a charm except: It seems that even though the data file poll interval is every 10 seconds, the digital display is only recalculated when the data file presents a new record. As a result, if the data file never receives a new record, the digital display will never be recalculated, and thus it will never display 'Not Available' even though the data is clearly older than 6 minutes.
My question: Is it possible to 'force' a digital display to recalculate its value on some frequency (say, every 30 seconds), even if the underlying data file has not been updated with a new record?
Any thoughts or comments would be appreciated.
You can define a virtual data source in RTMC pro and incorporate a reference to a variable from this source into your expression. This type of source has a refresh interval on which new records are generated.
As an alternative, take a look at the "No Data" alarm in RTMC Pro since this seems to do mostly what you want.
Thanks for your prompt reply! This solution works great. I set up a virtual data source in my project, with a value of '1' and an output interval of 10 seconds (for testing purposes). I then incorporated this data source into my calculations, and sure enough, the calculated values are updated regularly just as I expected.
I could use a 'No Data' alarm, but due to the criticality of the data being displayed (bridge air gap), to avoid any chance of confusion I would rather not have a value displayed at all than to have a stale value. I will probably incorporate a no data alarm as well.
I do still have an issue however: while this solution works very elegantly in RTMC Pro and RTMC run time, when I publish my project to the web using the web publisher tool, the desired functionality seems to be lost. Any further ideas or suggestions on this issue would be most appreciated.
Thanks!
If you are publishing the CSI Web Server, the virtual data source should still be supported. The place where it will NOT be supported is if you are publishing to the datalogger as a web server. In that case, only HTTP data sources are supported.
I am using the CSI Web Server. I am able to display the value from my virtual data source correctly on the web page, but my other digital displays do not recalculate and update as expected. Works fine in RTMC. I am at a loss with regard to publishing the page on the CSI Web Server, but at least I have the option of using RTMC.