Get NI Spy captures of both programs to see how they are operating differently, and what is being returned. If you are using RS-485, it is possible that you set the DTR with echo for the tranceiver mode in the program that is giving you the contents of the transmit buffer.
NI Spy TutorialThese two example programs may be of use to you when analyzing your spy captures.
Compare the Differences Between Two NI Spy Captures *requires MS Visual Studio* *Note: Use a simple compare*
Convert an NI Spy Capture into a Spreadsheet File *helpful for reformatting spy capture for easier printing*
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