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VISA viOpen timeout issue

Question asked by kwm on Jun 17, 2009
Latest reply on Jun 29, 2009 by dgun

I'm attempting to connect from an application to a two HP(/Agilent)35670A via a remote GPIB through the Aglient E5810A gateway as well as some other pieces of equipment. 

The physical layout of the network of equipment is as such that the computer I'm running my software at has an ethernet connection to a regular networking switch that has an ethernet connection a Keithley 2701 device and an ethernet connection to the E5810A gateway, which has 5 pieces of equipment (including the two DSAs mentioned previously) connected to that gateway via GPIB cables.

When running my software I'm opening a defaultRM session, and then using the viOpen function to open a session for each piece of equipment; all of this works as expected whenever I have all the equipment connected.  What I can't seem to get to work is the timeout attribute of the viOpen() method.  In my code I have a hard-coded timeout constant that is used for every session that is set to 500, and the hope was that this would limit the viOpen wait time to 500 milliseconds.  What I'm seeing is that the wait time is taking 5 seconds for the ethernet connection to the Keithley 2701, and 10 seconds for each of the two DSA's.  In my software, this is undesirable, because I would like to establish connections to the equipment when initializing, but I cannot afford to wait up to 10 seconds for every piece of equipment for which I'm opening a session.

I currently leave the access method as VI_NULL, but I've tried changing the access method to the VI_Exclusive and whatever the other mode is to see if that had any bearing or effect on the system, but did not see any change.

Is there another method of controlling this timeout period that I have overlooked, or am I missing a critical part of this equation?

Thank you for any help in advance.