A correctly designed alarm system is fundamental to most SCADA applications. Flexibility in the SCADA’s alarm handling is the key.

In PcVue an alarm is generated by a bit variable that has been configured with alarm behavior. This means that alarms have all the flexibility associated with a bit plus the characteristics required by an alarm. Changes in alarm value are time-stamped to millisecond resolution. The origin of the time-stamp can be PcVue itself or the source of the value (PLC, OPC etc.).
A real-time alarmlist is provided by the Alarm Viewer Alarms can also be used in the HMI’s animations the same as any other variable to produce color changes, change text strings, exchange symbols etc. Individual alarms can be accepted by an operator with the corresponding user rights. Advanced group alarm acceptance strategies can be configured using SCADA Basic.
In distributed applications alarms are broadcast to all nodes. Alarm acceptance (subject to user rights) can take place on any station.

Alarm counters


Alarm counters by level, status Domain and Nature are easily configured using specially named register variables. These can be displayed in the HMI and trigger actions (such as sending an email or generating an audible alarm) in the same way as any other variable.
Advanced alarm counters using expressions and alarm properties can be configured using a technique called alarm synthesis.

alarm counter 1


alarm counter 2

Alarm filters


The alarms visible in each viewer can be selected at run-time using the optional domain and nature filter. Additional, more complex filters, using any of the alarm variable’s attributes, can be constructed using scripts.

alarm filter

Alarm levels


PcVue supports 30 alarm levels. Alarm display, acknowledgment and masking levels can be different although for ease of configuration, by default, they are the same. These levels are also defined in the user profiles. Depending on his profile settings the user may be able to display, acknowledge or mask an alarm with a given level.

alarm level 1

Alarm Viewer


The Alarm Viewer displays a real-time list of alarms and can be embedded in any mimic. Each instance of the Alarm Viewer that you use is individually configurable.
Each alarm is displayed on a single line in a color reflecting its status and level. The alarm list can be sorted in a number of ways including display priority to the oldest, newest at the top or newest at the bottom.
The information that is displayed for each alarm is configurable and includes the following:

  • Alarm variable name, description, domain, nature, and level
  • Status including inhibited, masked and maintenance model
  • On, acknowledge and off time stamps in a configurable format
  • The value and type (hihi, high, low, lolo) for alarms produced by from the threshold behavior of a register variable
  • Up to eight configurable extended attributes including the value of other variables

alarm viewer 1

It is also possible to display the timestamp at which an alarm came on, was acknowledged and went off, all on the same alarm line:

alarm viewer 2

The alarm viewer can be configured to display a contextual popup open by a click on an alarm, allowing the display of any properties associated with the alarm. Also many contextual actions can be performed including but not limited to:

  • Open a specific mimic associated with the alarm
  • Add a pre-defined message or write a comment before acknowledgment
  • A tracking file associated to the alarm can be open for editing and saved
  • A procedure or a technical note can also be open by the operator (pdf,word,Excel,…),…

This popup is fully customizable.

alarm viewer 3



To help prevent alarm cascades, an alarm can be masked by another alarm, bit or an expression. Alarms can also be temporarily inhibited by the operator or taken out of service completely using maintenance mode.


Operator tools


Each Alarm Viewer includes a configurable toolbar from where the operator can display and change the Alarm Viewer filter, acknowledge, inhibit or switch alarms to maintenance mode, and execute an action associated with a particular alarm. (For example opening a mimic related to the alarm origin).

operator tool



A threshold is one of the behaviors that can be attached to a register variable. A threshold sets and clears a bit depending on the rising or falling value of the register and a configurable hysteresis. Up to four thresholds can be specified per register and can be used to directly generate alarms.

thresholds 1

thresholds 2