Detailed Description

The AlarmOperator triggers an alarm based on the input value. An AlarmOperator has no effect on the value. It sets output equal to input.

The AlarmOperator implements an alarm based on best practices from EEMUA Publication 191, and is an alternative to using CDPAlarm.

The AlarmOperator Argument In is used to control whether the alarm should activate or not. In is checked against Limit. The LimitType property specifies whether the alarm should trigger when In is Below the Limit or when it is above or equal to Limit. In addition, the arguments and properties explained in the tables below can be used to control the functionality of the alarm, such as blocking, deadband etc.

Arguments

Properties

When operator is used inside a signal its default input is automatically tied to signal's InternalValue or previous operator's output. Its default output is automatically tied to next operator's input or to signal's Value. See also CDP Operator Usage In CDP Signals.

Examples

Alarm when AboveOrEqual Value

Here is how the alarm behaves when the input signal varies, and the following settings are applied to the alarm:

1. When In value is above or equal to Limit the alarm is set.
2. When In value is below Limit the alarm is cleared.

Alarm when Below Value

Here is how the alarm behaves when the input signal varies, and the following settings are applied to the alarm:

1. When In value is below Limit the alarm is set.
2. When In value is above or equal to Limit the alarm is cleared.

Alarm with DelayOn

Here is how the alarm behaves when the input signal varies, and DelayOn with the following settings are applied to the alarm:

1. When In value is above or equal to Limit, the DelayOn timer is started.
2. When the DelayOn time (0.5 seconds in this case) has passed, and the alarm condition is still present, the alarm is set, and the DelayOn timer is stopped.
3. When In value goes below Limit, the alarm is cleared and the DelayOn timer is stopped.

Alarm with DelayOff

Here is how the alarm behaves when the input signal varies, and DelayOff with the following settings are applied to the alarm:

1. When In value is above or equal to Limit, the alarm is set
2. When In value goes below Limit, the DelayOff timer is started.
3. When the DelayOff time (0.5 seconds in this case) has passed, and the value is below Limit, the alarm is cleared, and the DelayOff timer is stopped.

Alarm Limit AboveOrEqual with Deadband

Here is how the alarm triggers on value AboveOrEqual, with Deadband, when the input signal varies and the following settings are applied to the alarm:

1. When In value is above or equal to Limit, the alarm is set
2. When In value goes below Limit - Deadband, in this case below 3, the alarm is cleared.

Alarm Limit Below with Deadband

Here is how the alarm triggers on value Below, with Deadband, when the input signal varies, and the following settings are applied to the alarm:

1. When In value is below Limit, the alarm is set
2. When In value goes above or equal to Limit + Deadband, in this case above 7, the alarm is cleared.

Alarm with OperatorBlocked

Here is how the alarm behaves when OperatorBlocked is applied, when the input signal varies and the following settings are applied to the alarm:

1. When In value is above or equal to Limit, the alarm is set
2. When In value is below limit, the alarm is cleared.
3. After triggering two times, OperatorBlocked is manually set to 1
4. Subsequent triggering of the alarm when OperatorBlocked is set does not cause the alarm to be set.

Alarm with ProcessBlocked

Here is how the alarm behaves when ProcessBlocked is applied, when the input signal varies and the following settings are applied to the alarm:

1. When In value is above or equal to Limit, the alarm is set
2. When In value is below limit, the alarm is cleared.
3. After triggering two times, ProcessBlocked is manually set to 1
4. Subsequent triggering of the alarm when ProcessBlocked is set does not cause the alarm to be set.

Conceptual Illustration of Deadband, DelayOn and DelayOff

1. Input value is above or equal to Limit, but since DelayOn time is specified, the setting is delayed.
2. DelayOn time is reached while alarm condition is still met. Alarm is set here.
3. In value is below Limit - Deadband, so alarm should be cleared, but since DelayOff time is specified, clearing is delayed.
4. DelayOff time is reached so alarm is no longer set here.

Actual Processing Code of the AlarmOperator

unsigned int AlarmOperator<T>::Process()
{
  d->If_Acked_AckAlarmAndClearRepeatBlockedAndRepeatCount();
  d->If_ResetTimesActivatedChangedTrue_ResetTimesActivated();

  d->SetOrClearOperatorBlockedStatus();
  d->SetOrClearProcessBlockedStatus();

  d->If_OperatorBlocked_UnackClearAndBlock();
  d->If_ProcessBlocked_ClearAndBlock();

  if(!d->IsBlocked())
  {
    d->DecrementRepeatCount();
    d->CheckHighLevelAndSetOrClearAlarm();
    d->CheckLowLevelAndSetOrClearAlarm();
  }
  d->If_StatusChanged_SendEventsAck_ClearOrSet();

  m_output = m_input;

  if (d->status!=d->lastStatus)
    if (auto parent = GetParent())
      parent->RunInComponentThread([=](){ parent->UpdateStatus(GetNodeID(), d->status); });

  d->StoreLastValues();

  return Status();
}