Another RSView32 Trend Question - auto pause?

tvey

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Join Date
Mar 2005
Location
Halifax, NS
Posts
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I am using the standard RSView32 trend control to display process data for several machine variables.

The trend pens are configured as below where #1,#2,#3 are parameters passed to the display and which correspond to the tag database path for the machine variable I am interested in trending:

Pen 1: #1\#2\#3\UpperTol
Pen 2: #1\#2\#3\Measured
Pen 3: #1\#2\#3\LowerTol

The first time I call the display, the trend automatically updates according to the update rate in the 'Trend Configuration tab' (2 seconds, in my case).

However, if I close the display and re-open it passing different parameters for #1,#2,#3, the trend will display the correct data but will no longer update automatically.

If I set the trend\pause tag to '0', the trend seems to perform a 'one-time' update and then automatically resets the 'pause' tag to '1'. I can reset the 'pause' tag any number of times and the trend will update and then pause itself again. If I restart the RSView app, the trend will auto-update just fine until I close it and re-open with different parameters.

This behaviour seems to occur for both historical and real-time trends.

This app has perhaps 120 different variables to trend, so I definitely like the idea of using RSView's version of indirect tags instead of creating 120 separate trend displays.

Does anyone have any insight into this issue?


-Trevor
 
I have had a different issue with control tags in native trending and found TrendX which is an add on to RSView 32 was far better for resolving my issues its on your RSView 32 disks
 
Yeah, I played around with TrendX a little bit but didn't see an easy way to change pens on-the-fly via indirects (parameter passing in RSView).

I'd like to have a single trend display rather than 120+! I guess I could configure 120 separate TrendX pen files, but again that seems like the long way around what should be a simple procedure. (I'll spare you the WW vs. RSView rant!)

For part of my TrendX testing, I wrote a small vb script that can remap the node name & address for a given tag at runtime. I then configured TrendX with 3 tags named 'IND_Pen1, IND_Pen2, IND_Pen3'. The 'IND_PenX' tags are remapped on demand to point to whatever process variable I'm interested in trending. The downside to this of course is that you end up with no good way to view historical data since the IND_PenX tags may have been used to display data for any number of variables at any point in the past. Works fine for real-time trending only though.

All that being said, I like the simplicity of the native RSView trend control. Parameter passing seems to work just fine with the exception of the strange 'auto-pause' behaviour I described in the first post.
 
The issue I had with RSView native trending was with the pause button which TrendX dealt with.
As for indirect tags I have never tried
By reading your post you say,
it works fine for real time trends only,
I use Historical data for nearly all my trending with no problems,
I use both native and TrendX and I find TrendX far simpler to deal with

Although as I said I dont use indirect tags
 
Quick follow-up to cap this thread:

I never did discover the root cause for the auto-pausing of the trend after re-displaying with different parameters.

I did come up with an ugly workaround. It doesn't solve the problem but it does give the appearance of an auto-updating trend.

I noticed that the trend control tag "trend\NewestTime" was consistently updated as the datalog captured data, so I created an event to look at it:


Event Expression:
(bAutoPauseOverride == 1) && (trend\starttime <= trend\Newesttime)

Event Action:
&Set trend\starttime trend\Newesttime;
&Set trend\Paused 0


I ended up with the above Event since simply resetting the 'Paused' bit didn't seem to work consistently.
I replaced the standard 'pause/resume' button with a button that toggles 'bAutoPauseOverride' instead.

The trend now updates at the same rate the datalogger logs new data, and there don't appear to be any problems after redisplaying the trend with different parameters.

Not the most elegant solution but it seems to get the job done without regular manual intervention to 'unpause' the trend.


-Trevor
 

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