In order to set control limits for your chart sets, SPC provides you with several different options. If you know the limits that you want to set, you can use Points or Values. If the process is new and you would like to have limits calculated automatically for you, you can use the auto recalculation features. Whatever your preference, SPC provides you with an option.

You can specify values for control limits by:

Entering values, or

Using auto recalculation.

You can enter values as:

(Specific) values.

Points.

 Caution: If you enter specific values during configuration and SPC detects an inconsistency, it will display an error message and will not allow you to save the configuration until you correct the error.

Example

You select Values to enter a variable's control limits and enter 25 for an Upper Control Limit and 50 for a Lower Control Limit. SPC will display the following error message, "The upper control limit must be greater than the center line and the center line must be greater than the lower control limit."

 Note: If you use Points for general characteristics on limits rather than specific values, SPC will alert the user when the values become specific at runtime. If SPC detects configuration inconsistencies, it will display an $SPC_ADMIN_ALARM in the Alarm Viewer.

More information

Step 3.4. Set limits for variable quality characteristics.

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