Deactivate Trigger configuration

For each trigger point that initiates a change to alarm limits, a corresponding deactivating trigger point can be configured. The fields on the Deactivate Trigger row are used to deactivate the hold. Use of a deactivating trigger point is optional, as the alarm limit changes will expire according to other parameters assigned with the activating trigger. This functionality serves to deactivate the hold.

Example

An example of how the deactivating trigger might be used is demonstrated by the following case:

The Deactivate Trigger is used when both ends of a pipe are closed (also known as a shut-in state), where the (negative) adjustment is set to occur indefinitely using the Hold Persist checkbox (opening the pipe). At this point, the deactivate trigger is triggered and the valve opens—ending the shut-in state.

To deactivate Trigger Configuration

1. Select the checkbox under the Trigger column, beside the Deactivate Trigger label.

2. Using the selection function for the field in the Point Path column, select the table, record, and field desired. Rules for selection depend on type of trigger.

   • If the trigger type is State — The table selected must be status, multistate, or analog.

     The field selected is irrelevant. State of the trigger point is determined by the text of the message string in the message table record that is currently assigned to the point as its current message.

   • If the trigger type is Value — Only analog table may be selected.

     The field selected must be of double type.

3. If State trigger is selected:

   • Type the triggering state in the State column text box. When the current state of the point changes to the state matching the configured triggering state, the alarm limit will be restored to the configured values.

4. If Value trigger is selected:

   1. Type the triggering value in the text box of the Value column.

   2. Select the comparison Controller from the dropdown of the Comparison Operator column. When the current value of the point field changes such that the relationship to the configured value becomes true when the comparison is applied, the alarm limit will be restored to the configured values.

Making configuration changes while in transient state

When an activation trigger is set for a given term, the dynamic configurations (Adjustment Type, Upper Deviation Limit Adjustment, Lower Deviation Limit Adjustment and Decay Time) are used to calculate the adjustments and the decay slope. Any updates made to these values while the PLM term is in a transient state will not take effect until the next activation. Therefore, it is recommended that you only make changes to the base limits and the dynamic configurations when the PLM term is not in a transient state.

If you make changes to the base limits while the PLM is in a transient state, the adjusted limit will be calculated as follows:

Adjusted Limit = New Base Limit + Adjustment (as calculated when the activation trigger was set).

That is, when an activation trigger is set, an adjustment is calculated using the base limits and the adjustment factors, as configured at the time of activation. For example, if the adjustment factor is 2 and the base limit is 100, the system performs the following calculation:

Adjustment = Base Limit × Adjustment Factor = 100 × 2 = 200

The Adjustment calculated at activation time is applied each processing cycle to the current value of the base limit. For example:

• If the base limit did not change since the activation trigger was set, the system performs the following calculation:

  Adjusted Limit = Base Limit + Adjustment = 100 + 200 = 300

• If the base limit changed to 140 since the activation trigger was set, the system performs the following calculation:

  Adjusted Limit = Base Limit + Adjustment = 140 + 200 = 340