About Process Control rules

A Process Control rule with defined conditions consists of a set of conditions for tag values. You can bind multiple conditions with the logical operators AND/OR. When using multiple conditions, you can specify the priorities that will determine the order in which conditions in the rule are applied. An event is registered when the conditions defined in a rule are satisfied. You can select the necessary event type for a rule. A rule can contain no more than eight conditions.

A rule containing a Lua script consists of a script in the Lua language containing a description of the algorithm used for event registration.

If you are using Lua scripts to create Process Control rules, you can use a global script, which is a Lua script in which global variables and Lua functions are initialized. You can use these global variables and functions in a Lua script for any particular rule. A specified global Lua script is automatically executed when the security policy is applied. When a security policy is created, the global Lua script is empty and does not contain executable code. A security policy can have only one global Lua script, which can be viewed and modified when working with any rule containing a Lua script.

The settings of a Process Control rule are displayed in the editor area that appears under the rule list when adding or modifying a rule.

In the left part of the rule editor area, you can configure the following settings:

• Rule name and description.
• For rules in which conditions are defined for the values of tags, you can configure the settings of conditions whose violation will cause an event to be registered. For information about conditions, please refer to the Types of conditions for the Process Control rules section.
• For rules consisting of a Lua script, you can configure the type of Lua script (Rule script or Global script) and the text of the Lua script. When creating a rule script, the entry field displays a Lua script template with brief comments. You can use the help button above the script entry field to open a window containing detailed comments for creating a script. For information about the applied functions and variables, please refer to the Functions and variables for a Lua script section.

In the right part of the rule editor area, you can configure the type of event that will be registered when the rule conditions are satisfied.

You can use the Event drop-down list to select an existing event type or add a new type. The following control buttons are located next to the drop-down list:

•  – edits the selected event.
•  – adds a new event.

An event type in the rule editor area uses the same event type settings that are provided on the Configure events tab.

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