When using Easy Chart save Data for Excel , 30 data points are displayed per second for the same tag.
How do I change this? I would like to display 1 data point per tag per minute.
The tag is using Historical Scanclass and has a deadband of 0.1.
Chart mode is RealTime with a poll rate of 1.
I had this same issue. I called in support. If I remember tomorrow I will dig through my email and post back. I think this happens to ever new easy chart. Export data from all your charts to check. That caused me some grief beforeā¦
Response A)
It looks like the data is duplicated but I donāt think it is. The values for the tags are different but the timestamp looks the same. If you are logging the value faster than one second we just simply arenāt showing the milliseconds on the export. Make sure you donāt have 2 tags logging in the historian or with the transaction group (whichever you are using). If you still canāt see it call into our tech support so we can look at the live system.
Response B)
This is probably happening because the default Aggregation mode on your pens is Min/Max. This means that when there are two or more values in a time slice, both the min and max values are recorded. Go into the Easy Chart customizer and edit each pen to change this mode.
Info A)
Sample Size and Aggregation Mode
The sample size determines how the query results will look. A Natural query will look up the logging rate for the queried tags, and return results spaced apart at that rate. This means that the return size will vary with the date range. An On Change query will return points as they were logged. This means that the results may not be evenly spaced. A Fixed query will return the given number of rows. Where data was sparse, interpolated values will be added. Where data is dense, the Aggregation Mode will come into play.
The Min/Max aggregation mode will return the min and max for every timestamp. The Average aggregation mode will return the average timestamp for data within the underlying range.
Info B)
The return size determines how the underlying data is aggregated and/or interpolated. If a distinct return size is specified, that will be the number of rows in the resulting dataset. The special numbers 0 and -1 mean āNaturalā and āOn-Changeā, respectively. āNaturalā calculates a return size based on the rate of the logging historical scan classes. For example, if you query 1 hour of data for a scan class logging every minute, the natural return size is 60. "On-Change means that youāll get an entry whenever any of the tags under consideration have changed.
Instead of defining a fixed return size, the parameters intervalHours and intervalMinutes can be used. These parameters can be used independently or together to define a āwindow sizeā. For example, if you defined a 1 hour range, with intervalMinutes=15, you would get 4 rows as a result.
The span of the query can be specified using startDate and endDate. You can also use rangeHours and rangeMinutes in conjunction with either start or end date to specify the range in dynamic terms. For example, you could specify only ārangeHours=-8ā to get the last 8 hours from the current time. Or you could use āstartDate=ā2012-05-30 00:00:00ā, rangeHours=12ā to get the first half of the day for May 30th, 2012.
The aggregation mode is used when the data is denser than what you asked for. This happens when using fixed return sizes, as there will often be multiple raw values for the window interval defined. Another common operation is to set the return size to 1, in order to use these aggregate functions for calculation purposes. The available functions are:
ā¢ āMinMaxā - will return two entries per time slice - the min and the max.
ā¢ āAverageā - will return the time-weighted average value of all samples in that time slice.
ā¢ āLastValueā - returns the most recent actual value to the end of the window.
ā¢ āSimpleAverageā - returns the simple mathematical average of the values - ((V1+V2+ā¦+Vn)/n)
Thing isā¦ I cannot find any ānaturalā settings in the easy chart properties or pen properties
I also looked at the tag history properties and did not find it there either.
Chart Mode is --Historical
A Natural query will look up the logging rate for the queried tagsā¦
Would be nice if this was clarified a little better. I would bet this issue is quite common.
Would be nice to hear from others in the forumā¦
Just found this post and it looks like I am having the same issue.
We plot set limit values (thresholds) along with our measured data values. Limit values are very rarely changed, but if someone changes a limit value from 10 to 20 they want to see a straight vertical line drawn from 10 to 20 for the exact time that the limit value was changed. Instead a diagonal line is drawn from 10 to 20 over a period of time and several extrapolated values can be seen via X-Trace.
I have tried using different aggregation modes and setting the line style to digital. (I have also tried changing the digital offset and digital gap as Iām not completely sure what the function of these properties is.) I have had better results where the line is still not completely vertical, but it is better in that the transition from starting value to ending value happens over a shorter time period and has less extrapolated values when using X-Trace. But still not what our users expect to see.
You can see a faster response in the return of historical data on the easy chart if you have a faster historical scan class. If you are storing historical data at the default historical rate then you may not see any kind of change to the chart until 10 seconds have passed. Where as if you are storing historical data at a 1 second rate you are going to see this change almost instantly. For the smoother transitions, where the data looks less block like, you can set the Value Mode, in Tag History, on the tag itself to Discrete.
My historical scan class was set to 5000ms, but even changing to 100ms doesnāt seem to make much difference. In this case we would actually like a completely block like chart rather than smooth transitions if there is a way to do that.
change your historical mode to digital instead of analog on each of your tags.
I have the Tag Pens property in the dataset set as Digital. Is this what you mean? Because I expected that to give me the block lines, but I still get the diagonal transitions.
I believe that diat150 was referring to the Discrete value mode on the tagās history settings (Edit Tag > History > Value Mode).
This will display vertical lines when the value changes. Unfortunately this will not change how the old data looks (weāre changing how the tag history is collected, not how it is displayed), but new tag history from this point on will show as vertical lines, instead of diagonal lines.
pscott (and diat150), thank you. Yes, that was the piece of information I needed, the pens in the chart are now being plotted as I want them. 