Display control rule violations
- Last UpdatedNov 26, 2024
- 2 minute read
The SPC Chart control does the following to display control rule violations:
-
Identify the control rules to be applied based on the QM specification of the latest filtered sample
-
Ignore any control rule that is not applicable to the characteristic or to the chart type
-
Enable rule checking for the identified control rules
The following table describes the control rules that the SPC Chart control supports:
|
Rule ID |
Description |
Alarm Text |
|---|---|---|
|
0 |
1 outside control limits |
H/L |
|
1 |
2 of 3 outside of 2 standard deviations |
H/L |
|
2 |
3 of 7 outside of 2 standard deviations |
H/L |
|
3 |
4 of 10 outside of 2 standard deviations |
H/L |
|
4 |
4 of 5 outside of 1 standard deviation |
H/L |
|
5 |
7 of 7 on one side of center line |
H/L |
|
6 |
8 of 8 on one side of center line |
H/L |
|
7 |
8 of 8 beyond 1 standard deviation* |
B |
|
8 |
9 of 9 on one side of center line |
H/L |
|
9 |
10 of 11 on one side of center line |
H/L |
|
10 |
12 of 14 on one side of center line |
H/L |
|
11 |
6 of 6 increasing or decreasing |
T |
|
12 |
7 of 7 increasing or decreasing |
T |
*This control rule is the only one not based on a trend (T) that can be violated by a combination of points on either side of the center line. All the other control rules require the specified number of points on the same side of the center line.
The control rules are evaluated based on the priority order specified in the Spc_Rule table. The chart displays control lines for the enabled control rules as defined below:
-
If rule IDs 1,2, or 3 are enabled, control lines are drawn at two standard deviations from the center line.
-
If rule IDs 4 or 7 are enabled, control lines are drawn at one standard deviation from the center line.
-
Rule IDs 5, 6, 8, 9, 10, 11, and 12 have no effect on the control lines.
Note: The control limits (at +/- 3 standard deviations) are always displayed on the chart.
The alarm text is used to indicate control rule violations as defined below:
-
H, if the violation occurs above the center line
-
L, if the violation occurs below the center line
-
B, if the violation occurs on both sides of the center line
-
T, if the violation is a trend and is not dependent on the position of the points relative to the center line
