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Overlapped Ethernet TCP/IP Transmissions on cRIO 9067?

Hi, all, 


I am maintaining and extending a LabVIEW 14.1 app that runs on a cRIO 9067. We developed our own FPGA in LabVIEW as part of this app.


It maintains a bi-directional communication path with an HMI running on a nearby PC (also written in LabVIEW). Regular status and data messages are sent from the cRIO to the HMI on a 10-second cycle.  The technology used for both directions of this pipeline is LabVIEW network streams.  The messages sent from the cRIO to the HMI are short -- a few hundred bytes each.


Every few hours, the cRIO app also transmits a 15 Mb file to an FTP server.  I've observed this process to take 15 seconds or so, whenever it's kicked off. For this operation, the software uses LabVIEW's built-in FTP protocol, first writing the data to a local file, and then requesting it to be sent to the server. The VI that does this operates at background priority.


My question is this: will the LabVIEW TCP/IP protocol overlap these operations? Or, is it possible that when the FTP transmission kicks off, it might disrupt the more routine message flow?  What I'm seeing in a network with 4 of these instruments is the cRIO randomly losing contact with the HMI, tossing a variety of seemingly unrelated exceptions.


As it turns out, the FTP server runs on the same machine as one of the HMIs. Would that make any difference?


Thanks for your help,


-- Mark

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