Suppressing or Managing “A Log Sample Was Missed” System Alarms in EcoStruxure Building Operation

[CraigEl]

Issue

Operators see excessive “A Log Sample Was Missed” system alarms in EcoStruxure Building Operation (EBO).
These alarms can flood the Alarm Viewer during device offline events, power outages, or heavy system load.
Users want to hide, filter, or suppress these alarms without losing visibility of higher‑priority alarms.

 

Product Line

EcoStruxure Building Operation

 

Environment

Building Operation WorkStation and Webstation

 

Cause

“A Log Sample Was Missed” alarms occur when:

• A device or interface goes offline
• The system is busy, impacting sample collection
• The log configuration is too frequent or uses small COV thresholds
• Power outages cause large numbers of logs to be missed simultaneously
• Existing system alarms are not yet reprocessed after Alarm Decorations are applied

These alarms are system alarms and cannot be disabled at the log object itself.

 

Resolution

Option 1 — Disable Trend Log when Device is Offline 

To prevent the “Log Sample Was Missed” alarm entirely, configure the Activation variable property of the Trend Log.

Steps

1. Open the Trend Log → Basic tab
2. Find Activation
3. Bind Activation to one of the following (in priority order)

• DeviceChanged property of the device
• Any property that reliably indicates online/offline
  

Expected behavior:

• When device goes offline → Activation = False
  Trend collection stops → No “log missed” alarms
• When device comes online → Activation = True → Logging resumes

Note:

Trend log Activation does not accept certain binding types (e.g., Device Status) in some EBO versions. If a property is not accepted, use DeviceChanged instead.

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Option 2 — Hide or Manage the Alarm Using Alarm Decorations 

Alarm Decorations can override default behavior for system alarms and automatically move these alarms to the Hidden Alarms section.

Steps (WorkStation):

1. Open WorkStation and navigate to:
   System → Alarms → Alarm Decorations

   

2. Click the “+” icon to add a new Decoration Rule.

3. Create a rule targeting the system alarm:

   • Field: System Alarm ID
   • Condition: Equals
   • Value: The ID for “Log Sample Missed”

     

4. Set Decoration Actions:

   • Auto-hide Override: True
   • Priority Override: (Optional) lower to non-operational priority
   • Category Override: (Optional) assign to a “System Alarms” category for filtering

     

5. Apply the rule.

6. Important: Existing alarms will not move until they are reprocessed.
   Do one of the following:

   • Acknowledge existing alarms
   • Wait for the alarm to occur again naturally
   • Trigger a new test condition to generate a fresh sample-missed event

Expected result: New “Log Sample Missed” alarms appear in Hidden Alarms, not in the main alarm list.

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Option 3 — Use Standard Alarm Filters (Works in both WorkStation and WebStation)

Some versions (e.g., EBO 4.0) may not show an Exclude option in Custom Alarm Views, but the standard alarm filter still supports filtering.

Steps (WorkStation)

1. Open the standard alarm viewer.
2. Right‑click inside the alarm list area.
3. Select Add Filter.
4. Choose Exclude for System Alarm ID.
5. Enter the ID for “Log Sample Missed”.
6. Apply and save.
   

   

Webstation 

In WebStation’s filter dialog, if wanting to hide/ exclude alarms within a specific Priority range, select “Not between”.
Because,
“Between” = show only alarms inside the range
“Not between” = show only alarms outside the range (i.e., exclude that range)

The above steps hides the alarms from this view without requiring Alarm Decorations.

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Option 4 — Disable Individual Alarms Manually

1. When the alarm appears, right‑click → Disable.
2. The specific log’s alarm will no longer reappear.

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Option 5 — Reduce Log Load to Prevent the Alarm Triggering

If alarms occur frequently for many logs:

1. Reduce the log sampling frequency.
2. Increase COV thresholds.
3. Investigate field device communication issues.
4. Check for overloaded AS or network issues.