It is important to understand a few key terms before continuing to read this chapter:
Alarm
An alarm is used to notify operators when a condition exists in your system that requires operator attention (e.g. a well level or tank pressure is low or high, a pump or motor is running or stopped, etc...) There are five basic alarm priorities: 0 – No Alarm (see Notification below), 1 – Critical, 2 - High, 3 – Warning, and 4 – Notice. Alarms must be acknowledged by operators so that the system knows they are aware of the situation. Alarms can be viewed and acknowledged either on the Alarm page or on your application pages with user interface tools from the alarm library.
Notification
The term notification is used for alarms that have been configured with a priority of 0 – No Alarm. Such alarms do not require operator acknowledgement, and can be used to make note of non-alarm conditions in your system.
Alarm Dialer System
VTS provides an optional Alarm Dialer System that has been designed to contact designated operators by phone, pager, and/or e-mail when alarms of a specific priority (or priorities) have been triggered, but have not been acknowledged for a user-defined period of time.
Event
An event is used to inform operators when a security-related incident has occurred or when an operator has performed a control action. Examples of security-related incidents include operators logging on or off and new user accounts being added. Examples of control actions include pumps being turned pump on or off and feed rates being set.
Events are reported to the History list on the Alarm page. The History list provides an excellent way to review everything that has happened in your system over a period of time.
Trigger Tag
The term trigger tag is used to indicate a tag whose value is being monitored by an alarm tag. It is the comparison of the trigger tag‘s value to a setpoint that causes an alarm to launch.
Some tags have built-in alarm capabilities and thus are their own trigger tags.
Alarm Tag
An alarm tag is a specialized type of tag that is part of the core VTS software. Its role is to monitor the value of a trigger tag, and trigger an alarm based on that value.
Note: Some tags have built-in alarm capabilities and do not require an alarm tag in order to launch alarms. Such tags are trigger tags and alarm tags in and of themselves.
It is possible to disable the built-in alarms for such tags, and associate them with alarm tags in the event that the built-in alarm parameters are not sufficient for your application’s needs. See: Overriding Built-in Alarms.
Alarm Priority Tag
An alarm priority tag is a specialized tag type that is part of the core VTS software. Alarm priority tags are used to specify alarm indicators such as the frequency of the alarm tones, the tone cycle, the alarm priority and alarm highlight color. Each alarm tag must have an alarm priority tag associated with it to control the actions that occur when the alarm is triggered.
Alarm Manager
The Alarm Manager is a VTS service that is responsible for monitoring and displaying alarms for a standard application. The Alarm Manager:
• Logs alarms and maintains all alarm information in a database; and
• Provides the default Alarm page
• Provides tools that you can use to develop customized alarm displays.