FTView - Trend Pro - Flat Lines Not Displayed

Hi All,

Developing a new application and deploying a historian.

In the past I mostly used the original Trend and had them setup with the historian tags so that operations can just click a button a view a trend. This was prior to having a historian and was via a local datalog

Now that I'm deploying a historian (along with new controls, migration to viewSE distributed, new HMI altogether) I'd like to use TrendPro instead of the original Trend. We will have a client in the managers office for watching the operation as well as being able to go to a TrendPro screen so the manager can search and add historical traces to get to whatever data they are looking for.

I have an issue on TrendPro trends where a flatline for an analog value doesn't show. It may also be true for a boolean that hasn't had a value change but I haven't tested that yet. I've tried adjusting sampling options and well as changing to linear interpolation in the trend properties. This is true no matter if it's a historical tag or a live tag. If I change the value of the tag, the changes will be reflected. It's as if there is a setting telling the trend to not sample, nor display, values that don't change. In the attached image the lower trace (green) reflects that. You can see towards the middle where I manipulated the data and it captures and displays that fine, however it will not show the flat lines on either side of this manipulated data.

If I put these tags in a traditional "non-pro" trend they display correctly, so that data is fine.

Appreciate any helps someone may have.

Are the data configured to exception reporting i.e. save on change only?

I.e. if the value of that green trend was constant from a time far earlier than (to the left of) the displayed plot's data, then there would be no data available in that time range to plot.

My brother says this should not be a problem, i.e. FTView knows to go back in time beyond the plot to get the previous value.

drbitboy said:

Are the data configured to exception reporting i.e. save on change only?

Click to expand...

I don't know where this would be configured, however it does it with live data as well as historical data. It displays correctly on a regular Trend tool. It's the TrendPro tool that does not display correctly.

I.e. if the value of that green trend was constant from a time far earlier than (to the left of) the displayed plot's data, then there would be no data available in that time range to plot.

Click to expand...

I believe the data is valid because it displays correctly on a Trend, I believe this is just a "TrendPro" thing. When I hover over the trace in TrendPro it shows the datatag is being "good" and has the correct current value, just won't display the flat line.

My brother says this should not be a problem, i.e. FTView knows to go back in time beyond the plot to get the previous value.

Click to expand...

My guess is that it has the value, just won't show the flat line.

Maybe there is an aliasing problem with the pixels. Can you change the size of the window?

drbitboy said:

Maybe there is an aliasing problem with the pixels. Can you change the size of the window?

Click to expand...

So, I think there may have been an aliasing issue that made me believe live data performed the same way, now I believe live data is performing as I would want it to and it's only historian data that is updating on change.

In the attached screen shot, the green is the historian tag. The brown at the bottom is the same tag but live data rather than from the historian.

The two mirror each other, but you can see the last horizontal line on the historian data isn't drawn. I could leave this for days and it won't ever draw the line until the tag value changes again. It's like it needs to see a start/end to a line before it can draw it. The same value on the brown (live data) tag below it shown. This is the behavior I want on the historian tags as it'll matter for showing PID setpoint targets and such when trending functions in the plant.

Again, a normal trend tool doesn't perform this way, so it's some behavior between the TrendPro tool and how it samples/displays historian data.