VISA file write works on 32 bit WIN 7 but not 64 bit

[MikeMack747]

I've got an application that has worked for years on several XP machines. It works on WIN 7 32 bit as well. It does NOT work on WIN 7 64 bit.

I download a file as a binary, break it into 4096 bit packets and send each packet via VISA write to a UUT. I've tried setting the program to run in XP mode, run as administrator. I suspect it's the VISA drivers, and I've downloaded and installed NI-DAQ 9.8 but I'm not having any luck 

[Dennis_Knutson]

Why would you install the daq driver, which has nothing to do with instrument communication, instead of VISA?

[MikeMack747]

I've installed Ni Max 5.6, Ni VISA 5.4.1, Ni Serial 4.0, and Ni 488.2.3.1.2

The VISA is the only one that seems to be amiss.

[Dennis_Knutson]

I'm posting by phone so I can't look at the VI. Can you post an image of the block diagram? I don't understand why a simple VISA Write would not work. Do you get an error? What exactly happens that makes you think it's not working?

[MikeMack747]

Everything works except my UUT, it sends a NAK on the first block of code and I do 10 retries with no luck. I can communicate with the instrument otherwise. VISA seems to work fine, it's more like the format of the message being sent is different during the code block file write.

[MikeMack747]

The icon isn't going to help much!

[Dennis_Knutson]

You haven't shown any of the code that uses VISA. I still can't think of a reason why a VISA Write would have a problem on a 64-bit os. If you suspect the file contents that you are writing, probe it and compare to your 32-bit system.

What NI serial device are you using?

[MikeMack747]

I'm using a CP2103 USB to RS-232 converter.

The VISA reads and writes are in the attached sub-vi's

[Dennis_Knutson]

Still posting from my phone.

NI-Serial is only for USB-Serial converters from NI so it's pointless to have it installed.

[BauerPower]

Mike, if you want to take a look at the commands being sent or received, you can run an IO Trace. It would be pretty easy to run an IO trace and take a look at the differences between the commands being sent in Win 7 32-bit and 64-bit. 

http://digital.ni.com/public.nsf/allkb/282C5D41E2BA04F2862574BA007803B9