Histogram Points

Histogram points record the frequency at which the value of a point, identified in the point_expression field, occurs within specific range intervals. This information is typically displayed graphically as a histogram.

Each time a new point sample is received, the counter for the range that includes the value in the histogram point is updated.

A histogram point must be configured as an array point. You must specify the number of elements in the array as six (6) greater than the number of range intervals you desire. The system uses the six additional array elements to maintain the following data:

The minimum of the point values received

The maximum of the point values received

The total number of samples received

The sum of the values of all samples

The number of sample values that were less than the lower limit of the point range (underflow bucket)

The number of sample values that were greater that the upper limit of the point range (overflow bucket)

The display_low_lim and display_high_lim fields are used to specify the lower and upper range values within which the point values are expected to occur. The range intervals are calculated based on these limits and the number of array elements specified.

A Reset condition occurs when the reset point is updated. This will cause the histogram array to be reset to zero or init_value (if it is defined).


The histogram point is a derived point with the calculation_type set to 10.

The number of elements in a histogram point equals the number of ranges plus six.

More information

Derived point file (DERIVED_POINT).