Performance of EventPipes with PISDK over high latency links

Discussion created by GBADI0 on Jan 16, 2012
Latest reply on Jan 16, 2012 by mhamel

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Hi,

I am building a processbook that will display events based on an event pipe in a list box using PB 3.2.3.0 with PI SDK 1.3.6.363

I have some code which looks like this which will build the eventpipes.

Private Sub ConstructEventPipes()
    
    On Error GoTo errHandle
    
    Dim objAlarm As PISDK.pipoint
    Dim i As Integer
    
    Set EventPipes = New Collection
    Set objEvents = New Collection
    
    For i = 1 To AlarmList.Count
        Log "Getting Event Pipe " & i & " of " & AlarmList.Count, "alarms.ConstructEventPipes"
        EventPipes.Add AlarmList.Item(i).Data.EventPipe
        
        VBA.DoEvents
    Next
    
errHandle:
    If Not err.Number = 0 Then Log err.source & ": " & err.Description, "alarms.ConstructEventPipes"
    On Error GoTo 0

End Sub

This works well over a local connection to the PI Server. With higher latency links the code gets exponentially slower through the for next loop.

Any suggestions on a better way to do this, or improvements to the existing code?

Thanks

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GBADI0 Jan 16, 2012 1:58 PM

Hi,

Realised my error here :-)

Best use one event pipe with a collection of points to monitor, something like this

Private Sub ConstructEventPipe()
   
    On Error GoTo errHandle
       
    Set objEvents = New Collection
    Set objEventPipe = objAlarmList.Data.EventPipe
    
errHandle:
    If Not err.Number = 0 Then Log err.source & ": " & err.Description, "alarms.ConstructEventPipe"
    On Error GoTo 0

End Sub

Much quicker now.

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mhamel

@ GBADI0 on Jan 16, 2012 2:08 PM

Hi Alexander,

I don’t see in your code a place where you invoke the Take or TakeAll methods to free up the queue of events. It seems that you add a reference to the entire EventPipe object every loop and that object contains more and more items. This would certainly go in line with the behaviour you observe that is exponentially growing.

Events accumulated in the EventPipe queue are represented by PIEventObject object in the PI SDK. You can extract them by invoking Take or TakeAll methods of the EventPipe member such as:

EventPipes.Add AlarmList.item(i).Data.EventPipe.Take

Tell me if that fixed your problem.

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2 Replies

GBADI0 Jan 16, 2012 1:58 PM
Hi,

Realised my error here :-)

Best use one event pipe with a collection of points to monitor, something like this
```
Private Sub ConstructEventPipe()
   
    On Error GoTo errHandle
       
    Set objEvents = New Collection
    Set objEventPipe = objAlarmList.Data.EventPipe
    
errHandle:
    If Not err.Number = 0 Then Log err.source & ": " & err.Description, "alarms.ConstructEventPipe"
    On Error GoTo 0

End Sub
```
Much quicker now.
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- mhamel @ GBADI0 on Jan 16, 2012 2:08 PM
  Hi Alexander,
  
  I don’t see in your code a place where you invoke the Take or TakeAll methods to free up the queue of events. It seems that you add a reference to the entire EventPipe object every loop and that object contains more and more items. This would certainly go in line with the behaviour you observe that is exponentially growing.
  
  Events accumulated in the EventPipe queue are represented by PIEventObject object in the PI SDK. You can extract them by invoking Take or TakeAll methods of the EventPipe member such as:
  
  EventPipes.Add AlarmList.item(i).Data.EventPipe.Take
  
  Tell me if that fixed your problem.
  Like • Show 0 Likes0
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Performance of EventPipes with PISDK over high latency links

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