Control Rules
- Last UpdatedOct 10, 2025
- 2 minute read
The following table describes the control rules that the SPC Chart widget 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. 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. For more information on control limits, see Chart Control Limits.
The alarm text is used to indicate control rule violations as defined below:
-
H - The violation occurs above the center line and indicates high alarm
-
L - The violation occurs below the center line and indicates low alarm
-
B - The violation occurs on both sides of the center line
-
T - The violation is a trend and is not dependent on the position of the points relative to the center line
Note: If there's no control rule violation, a single dash (-) is shown.
The color of the data point is determined by the alarm.
-
Red - High alarm
-
Blue - Low alarm
-
Green - No alarm