Hi Everyone!
Seems as though the Chart Graphic Element in Live may have some limitations, or I am not finding how to adjust the graphic.
1. In my notes from training, I have noted there is a limitation to 10 pens. When I created a chart today it appears that is the case. Anyone know of a good workaround for that limitation?
2. Can the legend be moved or are we limited to the legend to only being located under the chart? It would be great if we could stack it on the far right hand side column.
Thanks!
Jenny
The 10 pen limitation is baked in to the Embedded Live Trend. The work around would be to use multiple trends. As an example, the 20 pen CHART in PHV has grouping options to show some pens together in a different area. 20 pens on one chart is quite busy. Unlike PHV, the Live embedded CHART has 10 independent scales. (PHV uses scale for pen 6 on pens 7 and 8)
You cannot change the legend location. You can hide it, and call it up as needed. You cannot move it to the top.
As compared to DeltaV Operate or PHV trends, you cannot modify the pens in a Live embedded CHART, such as add a pen, change a pen, change the Pen Color or Description. You also cannot access the Time settings (neither read or write), which is pretty limiting. The Operator can scroll in time and the Overview bar is interesting, but launching the trend with a specific time frame or reading the Time window to retrieve related Event data from Event Chronicle is not possible.
I created a workaround, where the Pens are preconfigured for their Value and Scale parameters using Gem Variables. The Trend is created inside a GEM and the links are made to these string variables, with the Pen and scale using DLSYS[Gem.PV1] and DLSYS[Gem.SCALE1] allowing pen 1 to be redirected or defined at runtime. Unfortunately, the Pen descriptor cannot be manipulated on line.
I Created the GEM I use this in a Pop Up Trend contextual display instead of the PHV Charts. This allows me to have one PID loop Chart, with preconfigured descriptors like "PV value", "SP Value", and "OUT Value" and I tie the chart to the Module's primary function block, like PID1, AI1 etc, which are pass from the Faceplate.
The default legend is always at the bottom and offers the Value at the cursor. I also built a Gem that had a manual Legend that showed the actual Trend path strings (Mdoule/FB/Param) but that is limited in its history data. The Trend object does not expose the Curror time or values. The benefit of this though is that I could make the variables writable and allow the trend to be editable. The problem is the Pen Description cannot be changed. In the Trend legen, it would either be blank, or show the Module description associated with the pen.
In v15, the Table Object can be used to show the results of an Event Chronicle query. In this popup, I lock the time to 4 hours from current time and retrieve the events for that same time. Unfortunately, I cannot read the actual time span from the trend and if the user changes it, the Events window is still constrained and one cannot keep them aligned. So I added the PHV button that opens an adhoce ECHART, placing the same Variable paths into the CHS command line syntax. This removes the need to create a new PHV CHART named after specific Faceplate names as the adhoc chart is created from the Popup settings.
The other think I like about this are:
- Trend follows the THEME settings of Live
- The trend remains in LIVE and the Faceplate, Detail or event Control Studio buttons can be used to keep the operator connected to the related tag,
- the Tend pop up can be minimized and recalled.
In general, this is much easier to use as the pop up is always on its own. Calling up PHV calls up the last visualization and resizing a Chart inside of PHV need multiple clicks. You are limited to 6 CHARTS in the PHV window, and if these are already open, the PHV Button fails requiring you to close a chart and then try again. And if you forgot to add that prenamed chart in the PHV/LIB folder, the Chart is not available.
See my enhancement request and vote it up is you want Live Embedded Charts to get some love.
I've also used the embedded CHART Gem to create multi-Chart displays, which give you more pens. You can call this display up as a pop up or place it in your hierarchy. I use it in my Non-Hierarchy displays. Here I default to the standard Legend. Using the Variables to define the paths allows you to read these into a SQL query spanning all the trends, but the time for the query would need a manual adjustment ( we can read time of the trends). If I could read the time and write the time, I could control all trends in the display to the same time and also adjust the events to match. That would enable some interesting options. I also asked for the Cursor time to the read/write, allowing all trends in the display to have their cursor track one trend. Sweet.
Lots of potential, but users have to ask for it...
Andre Dicaire
In reply to Andre Dicaire: