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SystemLink 19.5 Dashboard Graph: How to speed up updates?

When I update a tag value on the server, it appears on my Dashboard Number tile almost 1 minute before it appears on the Dashboard Graph tile. In contrast, a Tag Viewer History graph is as responsive as a Dashboard Number tile.

 

How can I make the Dashboard Graph more responsive?

Certified LabVIEW Developer

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Hey JKSH,

We're using a couple different approaches to retrieve data for the Dashboard tiles. For the Dashboard Graph, we're retrieving decimated data every 30 seconds. This allows us to have a more accurate representation of long running data, where we don't mix and match decimated and non-decimated data. However, it looks like we could do more to help in your use case.

 

What time range are you using on the Dashboard Graph? Do you need to see real-time updates, or what polling interval would be sufficient for you?

Could you provide a little more context on your application?

Thanks!

Fred Visser -- SystemLink R&D -- National Instruments
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Hi Fred,

 

Thank you for your explanations.

 


@Fred_V wrote:

Could you provide a little more context on your application?


The story we wanted to present to our customer was, "SystemLink makes it very easy for you to visualize your live data in an intuitive manner". A Dashboard sounded like a good fit: It allows us to group related tags on a single page, plot trends, assign meaningful labels, and have all of this data is automatically updated.

Unfortunately, the chart tile updates every 30s while the number tiles around it update every 1s. This makes the chart feel frozen and unresponsive.

 

An example scenario: Our customer wants to experiment on power generators and expects the voltage output to remain steady at all times, and our customer would apply disturbances until a voltage deviation occurs. As soon as they observe a deviation, they would start taking other actions.

 

A 30s lag makes the Dashboard Chart tile unsuitable for this use case because it is not "live enough". In contrast, the Dashboard Number tile and the Tag History view are "live enough".

 

 


@Fred_V wrote:

What time range are you using on the Dashboard Graph? Do you need to see real-time updates, or what polling interval would be sufficient for you?


The time range was 1 hour.

 

I understand that "real-time" is harder when there's a large web server in the middle. Nonetheless, it would be great if the polling interval scales according to the time window (for example, poll every 2s if the chart window is 1 hour, poll every 30s if the chart window is 1 week or longer). It would be even better if we could manually change the polling interval (for example, under an "advanced setting" in the chart properties)

 

 


@Fred_V wrote:

For the Dashboard Graph, we're retrieving decimated data every 30 seconds. This allows us to have a more accurate representation of long running data, where we don't mix and match decimated and non-decimated data.


I do agree that it's good to have a way to avoid mixing decimated and non-decimated data (as the Tag History viewer currently does).

 

However, in our scenario, an unresponsive chart is a large issue while "avoiding mixing of decimated and non-decimated data" is a small benefit.

Certified LabVIEW Developer

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