Apis Online SPC
Apis offers online SPC monitoring of signals as part of the data validation feature, i.e. one of the data validation methods available is SPC.
How to set up a monitoring:
Create an item ("SPC Tag"). Add the following attributes: DvMethod = SPC, DvSPCUCL, DvSPCLCL, DvSPCTest and DvSubstMethod (optional) and set the appropriate values. Make the item you want to monitor ("Signal Tag") an external item to the "SPC Tag".
An alarm is triggered if one or more of the SPC tests fails. The alarm will be logged in the system log, but it is also possible to send it out as an e-mail notification.
SPC Test input codes
The set of SPC tests to apply when performing online SPC on a signal may be configured via the Apis attribute named "DvSPCTest". The table below lists the SPC tests and the code to use as input to "DvSPCTest". It is possible to select multiple tests. In such cases the input codes for the desired tests are entered as a semi colon separated list, e.g. 1;3;4.
| Input code | Short description | Description |
|---|---|---|
| 1 | 1BEYZA | One point beyond zone A |
| 2 | 9BEYCENT | Nine points in a row in zone C or beyond on one side of CL |
| 3 | 6INCDEC | Six points in a row steadily increasing or decreasing |
| 4 | 14ALTUPDO | Fourteen points in a row alternation up and down |
| 5 | 2OF3INZA | Two out of three points in a row in zone A or beyond |
| 6 | 4OF5INZB | Four out of five points in a row in zone B or beyond |
| 7 | 15INZC | Fifteen points in a row in zone C above or below CL |
| 8 | 8OUTZC | Eight points in a row on both sides CL with none in zone C |
Example zones and control limits
