Tutorial > Closed Loop Reaction > What is it

Sigma will shut down the process and notify you wherever you are even before the process goes out of control...

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What is Closed Loop Reaction?

Closed loop reaction essentially means that as long as the process is in control the software handles everything. No manual input or supervision is necessary. However, as soon as the process goes out of control, or even starts trending out of control, AT sigma SPC will shut down the process and alert the operator so that corrective action can be taken even before any defective parts have been manufactured, thus minimizing costs.We call this management by exception, which means that the operator should only be involved in the setup process and if something goes wrong. Users can be notified in any of the following ways: through sound, email and/or pager.

E-mail notification

AT-Sigma SPC will generate an Email message using SMTP, cc:mail or Microsoft compatible MAPI and send it to whomever needs to be notified. The message can include the station, variable information and selected charts.

A sample email message:

Email can be sent to local sites on a network, remotely to laptops or worldwide locations. Email notification has the benefit of using existing corporate communication infrastructure and allows saving, deleting, filtering, forwarding and copies to groups (cc) just like existing mail. Instead of going to look up charts, AT-Sigma SPC automatically sends them to you when the charts meet your criteria.

Pager Notification

In the same spirit as Email, AT-Sigma SPC can take a control event and use a modem to call a pager. This is an alternative notification method from Email in that Email is generated but you need to check your mail box or be on the computer to be notified. The Pager method can alert you to sensitive conditions for anyone who is not regularly at the PC desktop. On the manufacturing floor or jogging at lunch, never be without the information you need if you desire.


AT-Sigma SPC will even allow you to trigger a shutdown of the manufacturing process based on an out of control condition. AT Sigma SPC can be set up to run a specified program when certain defined conditions such as trending out of control occurs.

Corrective action View a Screen Cam demo.

The corrective action module forces logging of information in response to out of control conditions. When AT-Sigma SPC is operated in real time mode or told to update via DDE, it will analyze all defined control charts for stability and if any are out it will present the status grid to inform the operator of the nature and state of all charts, followed by the corrective action dialog below,

Causes and Reactions

You set up a list of possible causes for the operator to choose from when an SPC alert condition occurs. The list contains text descriptions and associates a numeric code for simple storage and processing. The list can contain over 32000 entries. Reactions is set up like causes and displays the action that is needed to be taken to resolve the situation.

When corrective action event is triggered, AT-Sigma SPC can require the operator to enter a few items from a list of possible reactions you create. It is simple to change from required to optional with proper access rights.


The operator can enter free-form comments when corrective action is triggered. These comments or notes can be useful in pointing to the cause. The comment is optional.

The comment, cause and reaction entries are, together, called a Tag. The Tag is information attached to the raw data record that adds description information external to the data.

The process button is for the on-line reaction plan. You can assign a process help when using SPC Setup. This automatic on line help system is designed to solve specific problems and facilitates fool proof corrective actions. The customizable on line help for operator assistance may be used for information on:

These reaction plans are useful when implementing ISO 9000 standards, since all the documented steps can be made available on line. Detailed on line reaction plans also help minimizing wasted time and mistakes, since the operator is shown exactly what needs to be done to remedy a specific situation. Help files can be saved in the format of your choice: Windows HLP files, HTML, Adobe Acrobat, Frammaker etc. This allows great flexibility and depth of information, as text, pictures, video and audio can be used to get a message across.

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