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E8257 losing TCP connection

Question asked by miyamky on Nov 9, 2016
Latest reply on Dec 8, 2018 by ozymandius

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We control all of our measurement equipment w/ SW. For only the E8257D synthesizers we have a random problem come up.

At a random interval, we will lose TCP connection to the device (seems like the instrument is just dropping the TCP connection). It happens to random synthesizers at random times. This is mostly a recent occurrence (no recent firmware upgrades). The synthesizer is at firmware C.05.37.

We did have this issue a while ago but we set the keep alive timeout to 75 seconds using setsockopt (from the default 60 mins) and that seemed to clear the issue until recently.

Restarting the SW clears the issue up (at least temporarily).

Any ideas?

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FrankC

Apr 24, 2017 3:08 AM

Sorry for the delayed reply. I saw no-one had responded to your question yet, so I spoke to one of our support engineers to get his advice.

He hasn't seen this problem before, and his recommendation is that the unit be returned for service. If he was to hazard a guess, then it could be a problem with the A21 rear panel.

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ozymandius @ FrankC on Dec 8, 2018 1:50 PM

I have seen something like this crop up with VNAs I am using. We use the VISA through a VB.NET script, but I think our problems could be similar.

Problem:

The VB.NET program would sit on the work station and take commands from our Ignition GUI/HMI from the user and execute them in the background. The VB script had an event loop where it would poll to check for commands from the user and then after that attempt a connection to the VNA. If it couldn't connect, it would inform the user.

We were having an issue where when the computer sat idle for a little while - no one using the GUI for a few seconds / minutes - the VB script would report it had lost the connection. Because we used an event loop, the error cropped up over and over again and the VB program would need to be restarted until the problem happened again.

Solution:

It turned out our VB program was leaving a connection open. In VB, it seems surprisingly difficult to truly close and destroy a connection. Found the code in one of Keysight's manuals...not sure which one...but here it is.

Public Function closenaconnection(ByRef instrument As Ivi.Visa.Interop.FormattedIO488, ByRef iomgr As Ivi.Visa.Interop.ResourceManager)
Try
instrument.IO.Close()
Catch ex As Exception
End Try
Try
System.Runtime.InteropServices.Marshal.ReleaseComObject(instrument)
Catch ex As Exception
End Try
Try
System.Runtime.InteropServices.Marshal.ReleaseComObject(iomgr)
Catch ex As Exception
End Try
End Function

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2 Replies

FrankC Apr 24, 2017 3:08 AM
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Correct Answer
Sorry for the delayed reply. I saw no-one had responded to your question yet, so I spoke to one of our support engineers to get his advice.

He hasn't seen this problem before, and his recommendation is that the unit be returned for service. If he was to hazard a guess, then it could be a problem with the A21 rear panel.
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- ozymandius @ FrankC on Dec 8, 2018 1:50 PM
  Mark Correct
  Correct Answer
  I have seen something like this crop up with VNAs I am using. We use the VISA through a VB.NET script, but I think our problems could be similar.
  
  Problem:
  
  The VB.NET program would sit on the work station and take commands from our Ignition GUI/HMI from the user and execute them in the background. The VB script had an event loop where it would poll to check for commands from the user and then after that attempt a connection to the VNA. If it couldn't connect, it would inform the user.
  
  We were having an issue where when the computer sat idle for a little while - no one using the GUI for a few seconds / minutes - the VB script would report it had lost the connection. Because we used an event loop, the error cropped up over and over again and the VB program would need to be restarted until the problem happened again.
  
  Solution:
  
  It turned out our VB program was leaving a connection open. In VB, it seems surprisingly difficult to truly close and destroy a connection. Found the code in one of Keysight's manuals...not sure which one...but here it is.
  
  Public Function closenaconnection(ByRef instrument As Ivi.Visa.Interop.FormattedIO488, ByRef iomgr As Ivi.Visa.Interop.ResourceManager)
  Try
  instrument.IO.Close()
  Catch ex As Exception
  End Try
  Try
  System.Runtime.InteropServices.Marshal.ReleaseComObject(instrument)
  Catch ex As Exception
  End Try
  Try
  System.Runtime.InteropServices.Marshal.ReleaseComObject(iomgr)
  Catch ex As Exception
  End Try
  End Function
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E8257 losing TCP connection

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