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All Places > PI Developers Club > PI Visualization Development > Blog > 2017 > May

There are a lot of users who want a SQC symbol in PI Vision, similarly to what exists in PI ProcessBook.

On the customer feedback site for PI Vision, there is currently 87 votes for such a feature.

If you also want this feature, please vote!

Until it gets implemented, I tried my best to mimic the PI ProcessBook's SQC symbol.

In particular, PI ProcessBook's SQC symbol displays histogram along with a trend overlay.

I tried to mimic this in PI Vision. (PI Coresight 2016 R2)

First, for displaying the histogram, I used this sample.


It can show histogram like following.

The limits (HiHi, LoLo, etc.) are computed using the following analyses and are stored as child attributes.


In PI Vision, I created the following display.

The trend contains the source attribute (in blue) and the limits are the dotted lines.

The red dots showing the exceptions that are created by the analysis too. (2017/05/15 Edited as Jerome's comments)


If the histogram does not appear, open the debug console and see if you get the following error:

“Too many points in dataset. Number of points is 401 and current limit is 400.“

You will need to either view the data over a smaller timerange or edit the custom symbol's source code.

In the PI Vision's "ext" folder open the sym-amcharts-histogram.js and add in the "Intervals" property as below.

Intervals represents the number of values the symbol will retrieve. Setting intervals to a large number can impact performance.


I am by no means an expert in SQC and in the statistics method involved.

If you have suggestions, please add them in the comments below.


I worked with Daniel Cho and Jerome Lefebvre  for creating this display.