Labview2009 error with Ke2700 on GPIB

[mais76]

Dear all,
I have to resolve a problem using the Keithley 2700 connected to the laptop with the KUSB-488A interface.

I'm developing an application with Labview 2009 to acquire 24 channels (1..12 Vdc and 13..24 Resistance) from the Keithely 2700 and its scanner KE7701. The application starts successfully and data is acquired correctly for a random time (for an hour, sometimes 3h, sometimes 4h, and so on), so the communication will be lost for some readings (all channels return 0), restarts to work correctly for limited time, lost again the communication and so on; all randomly.

To understand if the problem is or not in my application I get the example Keithley 27XX Advanced Scan.vi in the Keithley 27XX.lvproj downloaded from the Keithley website. I changed it to perform multiple readings after the initialization (see the attachment DiagramBlock.jpg) but also with this application I have the same behavior, the communication is not stable. So I added a log list to show you these errors (see FrontPanel.jpg). As you can see after 12 errors the application starts to work correctly because the data is different from 0, the application worked fine until i=381 than stopped to work at i=393 then I stopped the application after 7 successfully readings.

The Keithely 2700 has the firmware B09, and to develop the application I have done in order:
-) installed Labview 2009
-) uinstalled Ni Visa 488
-) installed KIOL-850C04

How can I resolve the problem?
Thanks in advance for your support.
Best regards
Alessio Pannocchia